Memory leak when calling `select_family_by_name`

[ginnyTheCat]

When being run using LeakSanitizer the following program is reported to leak memory. This oddly only happens on ubuntu (with fontconfig install from apt and even with a fontconfig build from main, maybe I compiled it wrong though idk) for me and not on my local machine (fedora).

use font_kit::source::SystemSource;

fn main() {
    let s = SystemSource::new();
    let font = s.select_family_by_name("serif").unwrap();
}

=================================================================
==109138==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 256 byte(s) in 1 object(s) allocated from:
    #0 0x56146dccaaef in malloc /rustc/llvm/src/llvm-project/compiler-rt/lib/lsan/lsan_interceptors.cpp:74:3
    #1 0x7fe5ee3737fc  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x227fc) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #2 0x7fe5ee377ed8  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x26ed8) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #3 0x7fe5ee386331  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x35331) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #4 0x7fe5ee235a6f  (/lib/x86_64-linux-gnu/libexpat.so.1+0xaa6f) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #5 0x7fe5ee236772  (/lib/x86_64-linux-gnu/libexpat.so.1+0xb772) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #6 0x7fe5ee237747  (/lib/x86_64-linux-gnu/libexpat.so.1+0xc747) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #7 0x7fe5ee239f70  (/lib/x86_64-linux-gnu/libexpat.so.1+0xef70) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #8 0x7fe5ee22f46e  (/lib/x86_64-linux-gnu/libexpat.so.1+0x446e) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #9 0x7fe5ee23c3cd in XML_ParseBuffer (/lib/x86_64-linux-gnu/libexpat.so.1+0x113cd) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #10 0x7fe5ee38083d  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x2f83d) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #11 0x7fe5ee38122c  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x3022c) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #12 0x7fe5ee381478  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x30478) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #13 0x7fe5ee384436  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x33436) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #14 0x7fe5ee235a6f  (/lib/x86_64-linux-gnu/libexpat.so.1+0xaa6f) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #15 0x7fe5ee236772  (/lib/x86_64-linux-gnu/libexpat.so.1+0xb772) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #16 0x7fe5ee237747  (/lib/x86_64-linux-gnu/libexpat.so.1+0xc747) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #17 0x7fe5ee239f70  (/lib/x86_64-linux-gnu/libexpat.so.1+0xef70) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #18 0x7fe5ee22f46e  (/lib/x86_64-linux-gnu/libexpat.so.1+0x446e) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #19 0x7fe5ee23c3cd in XML_ParseBuffer (/lib/x86_64-linux-gnu/libexpat.so.1+0x113cd) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #20 0x7fe5ee38083d  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x2f83d) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #21 0x7fe5ee38122c  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x3022c) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #22 0x7fe5ee3683b5  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x173b5) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #23 0x7fe5ee361751  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x10751) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #24 0x7fe5ee362f84 in FcConfigSubstituteWithPat (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x11f84) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #25 0x56146dcf12fd in font_kit::sources::fontconfig::fc::Pattern::config_substitute::h7dda7302f5a6b851 /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/font-kit-0.14.2/src/sources/fontconfig.rs:404:17
    #26 0x7fe5ee02a28a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28a) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
    #27 0x56146dcc6904 in _start (/abc/target/x86_64-unknown-linux-gnu/debug/abc+0xaa904) (BuildId: 6b43ccce9978bebb5c13f69b091cb57add85b7a4)

Objects leaked above:
0x510000000500 (256 bytes)

Indirect leak of 64 byte(s) in 2 object(s) allocated from:
    #0 0x56146dccad5e in calloc /rustc/llvm/src/llvm-project/compiler-rt/lib/lsan/lsan_interceptors.cpp:91:3
    #1 0x7fe5ee377e6f  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x26e6f) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #2 0x7fe5ee386331  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x35331) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #3 0x7fe5ee235a6f  (/lib/x86_64-linux-gnu/libexpat.so.1+0xaa6f) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #4 0x7fe5ee236772  (/lib/x86_64-linux-gnu/libexpat.so.1+0xb772) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #5 0x7fe5ee237747  (/lib/x86_64-linux-gnu/libexpat.so.1+0xc747) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #6 0x7fe5ee239f70  (/lib/x86_64-linux-gnu/libexpat.so.1+0xef70) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #7 0x7fe5ee22f46e  (/lib/x86_64-linux-gnu/libexpat.so.1+0x446e) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #8 0x7fe5ee23c3cd in XML_ParseBuffer (/lib/x86_64-linux-gnu/libexpat.so.1+0x113cd) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #9 0x7fe5ee38083d  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x2f83d) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #10 0x7fe5ee38122c  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x3022c) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #11 0x7fe5ee381478  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x30478) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #12 0x7fe5ee384436  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x33436) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #13 0x7fe5ee235a6f  (/lib/x86_64-linux-gnu/libexpat.so.1+0xaa6f) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #14 0x7fe5ee236772  (/lib/x86_64-linux-gnu/libexpat.so.1+0xb772) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #15 0x7fe5ee237747  (/lib/x86_64-linux-gnu/libexpat.so.1+0xc747) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #16 0x7fe5ee239f70  (/lib/x86_64-linux-gnu/libexpat.so.1+0xef70) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #17 0x7fe5ee22f46e  (/lib/x86_64-linux-gnu/libexpat.so.1+0x446e) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #18 0x7fe5ee23c3cd in XML_ParseBuffer (/lib/x86_64-linux-gnu/libexpat.so.1+0x113cd) (BuildId: 2a3ae4a996d521e6f1d4f95f4d1ea03549204262)
    #19 0x7fe5ee38083d  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x2f83d) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #20 0x7fe5ee38122c  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x3022c) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #21 0x7fe5ee3683b5  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x173b5) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #22 0x7fe5ee361751  (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x10751) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #23 0x7fe5ee362f84 in FcConfigSubstituteWithPat (/lib/x86_64-linux-gnu/libfontconfig.so.1+0x11f84) (BuildId: 9ea8985291d6ca9e904a796a5767d191039d813d)
    #24 0x56146dcf12fd in font_kit::sources::fontconfig::fc::Pattern::config_substitute::h7dda7302f5a6b851 /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/font-kit-0.14.2/src/sources/fontconfig.rs:404:17
    #25 0x7fe5ee02a28a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28a) (BuildId: 42c84c92e6f98126b3e2230ebfdead22c235b667)
    #26 0x56146dcc6904 in _start (/abc/target/x86_64-unknown-linux-gnu/debug/abc+0xaa904) (BuildId: 6b43ccce9978bebb5c13f69b091cb57add85b7a4)

Objects leaked above:
0x502000025de0 (32 bytes)
0x502000025e40 (32 bytes)

SUMMARY: LeakSanitizer: 320 byte(s) leaked in 3 allocation(s).