zstd-sys leaks build dir location

[lumag]

Attempting to build a crate using zstd-sys in Yocto results in a QA error, 'QA Issue: File /usr/bin/.debug/igt-runner in package deqp-runner-dbg contains reference to TMPDIR'. This happens because zstd-sys leaks source directory location to the generated binary:

strings usr/bin/.debug/* | grep cargo_home
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6
/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/armv8a-linaro-linux/deqp-runner/0.20.0/sources-unpack/cargo_home/bitbake/zstd-sys-2.0.11+zstd.1.5.6

Please consider fixing generated debug information in order to generated reproducible builds.