Sanitize the behavior of -Wcoverage-mismatch.

2010-05-04  Neil Vachharajani <nvachhar@google.com>

        * doc/invoke.texi (-Wcoverage-mismatch): Updated documentation as
        per new semantics.
        * opts.c (decode_options): Enable -Werror=coverage-mismatch.
        * coverage.c (get_coverage_counts): Always emit a warning.  Adjust
        conditions for printing notes.
        * common.opt (-Wcoverage-mismatch): Allow negative, default to
        true, update documentation.
        * Makefile.in (coverage.o): Add dependence on DIAGNOSTIC_H and intl.h.
        * testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c: Adjusted.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@159050 138bc75d-0d04-0410-961f-82ee72b054a4