Update gnome-code-coverage.m4 from gnome-common to fix some (harmless)
error messages when coverage is disabled (bug 699943), and to add
support for lcov 1.10.
Use the following in Makefile.am to enable code coverage for individual modules:
@GNOME_CODE_COVERAGE_RULES@
my_program_LIBS = … $(CODE_COVERAGE_LDFLAGS) …
my_program_CFLAGS = … $(CODE_COVERAGE_CFLAGS) …