Won't compile on ARM

[MagaTailor]

rust-lang/rust#29867 says hello:

Compiling capstone v0.0.0 (https://github.com/ebfe/rust-capstone.git#487e5951)  
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:68:81: 68:85 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:68             Error{ code: err, desc: Some(String::from_utf8_lossy(CStr::from_ptr(cstr).to_bytes()).to_string()) }
                                                                                                                                                                      ^~~~
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:68:81: 68:85 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:116:64: 116:97 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:116                             mnemonic: from_utf8(CStr::from_ptr(ci.mnemonic.as_ptr() as *const i8).to_bytes()).unwrap_or("<invalid utf8>").to_string(),
                                                                                                                                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:116:64: 116:97 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:117:64: 117:95 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:117                             op_str:   from_utf8(CStr::from_ptr(ci.op_str.as_ptr() as *const i8).to_bytes()).unwrap_or("<invalid utf8>").to_string(),
                                                                                                                                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/git/checkouts/rust-capstone-4618044b7fb862b2/master/src/lib.rs:117:64: 117:95 help: run `rustc --explain E0308` to see a detailed explanation
error: aborting due to 3 previous errors
Build failed, waiting for other jobs to finish...
Could not compile `capstone`.

In most cases it's enough to do a cast as *const _ while the rest might require coercion via a variable.

I was using a 1.7 armv7 nightly.

[ebfe]

Should be fixed.