system/kbd: fix some regressions in newer releases

Since kbd=2.0.4, three regressions have been discovered:

• CFLAGS were being overriden. Fixed by https://github.com/legionus/kbd/commit/15a74479f904f6b15f31854455656710e9aa1942

• loadkeys -d would fail if defkeymap.map.gz was a symlink. Fixed by https://github.com/legionus/kbd/commit/acf93e44f6d036303f95555069031f6fb12ce9d1

• setfont would fail if its argument was a compressed font file. Fixed by https://github.com/legionus/kbd/commit/7e27102b6fc6991a6a4eca422b513781a26b1639

Since the last commit introduced new binary files for the test suite, use a handrolled tarball with the changes instead of patching.