[feature] pkg_config/PkgConfigDeps generators: -Wl,-rpath="${libdir}" should be removed

[SpaceIm]

• I've read the CONTRIBUTING guide.

Currently (conan 1.30.1, but for a long time), pkg_config generator creates a pkg-config file like this on Linux:

prefix=/home/spaceim/.conan/data/h3/3.7.0/_/_/package/7fe67a73ac24eef3dbbe871cec7ad5a0356f543a
libdir=${prefix}/lib
includedir=${prefix}/include

Name: h3
Description: Hexagonal hierarchical geospatial indexing system.
Version: 3.7.0
Libs: -L${libdir} -lh3  -lm  -Wl,-rpath="${libdir}"
Cflags: -I${includedir} -DH3_PREFIX=

When this pkg-config file is consumed in another project to produce an executable or shared lib, rpath is hardcoded in this runtime file. It leads to some inconsistent behaviour where some paths are in rpath and others not depending on whether the lib has been consumed through pkgconf or not in build system of a recipe.
Moreover, those kinds of absolute RPATH hardcoded in runtimes don't make sense at all for binaries produced on another machine.

"Official" pkg-config files usually never have -Wl,-rpath in Libs.

[SpaceIm]

@czoido @memsharded Did you remove -Wl,-rpath in PkgConfigDeps?

EDIT: nop, still there.