Re: [libvirt] [PATCHv4] build: restore operation of bit-rotted 'make cov'

'./autobuild.sh' with lcov installed discovered that our coverage support has been bit-rotting for a while. This restores it back to a successful state, although I have not yet spent any time looking through the resulting files to look for low-hanging fruit in the unit test coverage front. * configure.ac: Clear COMPILER_FLAGS at right place. * Makefile.am (cov): Newer genhtml no longer likes plain -s. * m4/compiler-flags.m4 (gl_COMPILER_FLAGS): Don't AC_SUBST COMPILER_FLAGS; it is a shell variable for use in configure only. * src/Makefile.am (AM_CFLAGS, AM_LDFLAGS): New variables, to make it easier to provide global flag additions. Use throughout, to uniformly apply coverage flags. * .gitignore: Globally ignore gcov output. * daemon/.gitignore: Simplify. * src/.gitignore: Likewise. * tests/.gitignore: Likewise. --- v3 had an ACK at: https://www.redhat.com/archives/libvir-list/2010-June/msg00660.html but I never applied it because it was part of a larger series that had not been completed. I'm now at the point where this is easy enough to include in 0.8.3, while leaving the docs VPATH fixups for post release, but it has changed enough to need another ACK before I can push. Changes from v3: rebase to present status (several conflicts resolved in src/Makefile.am) fix 'cov' rule in Makefile.am to allow VPATH usage