re PR libstdc++/47058 ("--enable-maintainer-mode --disable-werror" wrongly upgrades warnings to errors in libstdc++)

2012-02-17  Benjamin Kosnik  <bkoz@redhat.com>

	PR libstdc++/47058
	* acinclude.m4 (GLIBCXX_ENABLE_WERROR): New.
	(GLIBCXX_EXPORT_FLAGS): Add -Wabi to WARN_FLAGS
	* configure.ac: Use it.
	* fragment.am: Set WERROR_FLAG conditionally on --disable-werror.
	* configure: Regenerate.
	* python/Makefile.in: Same.
	* Makefile.in: Same.
	* doc/Makefile.in: Same.
	* include/Makefile.in: Same.
	* po/Makefile.in: Same.
	* python/Makefile.in: Same.
	* src/Makefile.in: Same.
	* src/c++11/Makefile.in: Same.
	* src/c++98/Makefile.in: Same.
	* testsuite/Makefile.in: Same.

From-SVN: r184349