Build: Fix timestamps in generated tarball.
Build: Fix timestamps in generated tarball.

The debian buildchain requires generated tarballs to have the
same timestamps to be considered equal. So, set the timestamps
of generated files to the git commit date.

stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc