Add -D_GLIBCXX_ASSERTIONS to DEBUG_FLAGS
Enable assertions in the extra debug library built when
--enable-libstdcxx-debug is used. Replace some Debug Mode assertions
in src/c++11/futex.cc with __glibcxx_assert, because the library will
never be built with Debug Mode.
* configure: Regenerate.
* configure.ac: Add -D_GLIBCXX_ASSERTIONS to default DEBUG_FLAGS.
* src/c++11/futex.cc: Use __glibcxx_assert instead of
_GLIBCXX_DEBUG_ASSERT.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@263235 138bc75d-0d04-0410-961f-82ee72b054a4