[PATCH] Add support for coverage (compiling for gcov)

Hi!

We've added support for gcc --coverage (including -fprofile-arcs and -ftest-coverage) to ccache.

You can find the patches, for the maint versions, over on https://github.com/itension/ccache:

https://github.com/itension/ccache/compare/3.1-maint...coverage-3.1.10.patch

https://github.com/itension/ccache/compare/3.2-maint...coverage-3.2.1.patch


It works by storing the .gcno file in the cache (next to the .o file), when using --coverage.

It also needs to hash the absolute path to the .gcda file, that is created later at runtime.


Please include these in ccache, under GNU General Public License v3. I am their author.

/Anders