configure.ac (--enable-linux-futex): Add new configure option.

configure.ac (--enable-linux-futex): Add new configure option.

libstdc++-v3/
	* configure.ac (--enable-linux-futex): Add new configure option.
	(HAVE_LINUX_FUTEX): New AC_DEFINE.
	* Makefile.in: Rebuilt.
	* aclocal.m4: Rebuilt.
	* configure: Rebuilt.
	* config.h.in: Rebuilt.
	* config/cpu/generic/cxxabi_tweaks.h (_GLIBCXX_GUARD_BIT,
	_GLIBCXX_GUARD_PENDING_BIT, _GLIBCXX_GUARD_WAITING_BIT): Define.
	* config/cpu/arm/cxxabi_tweaks.h (_GLIBCXX_GUARD_BIT,
	_GLIBCXX_GUARD_PENDING_BIT, _GLIBCXX_GUARD_WAITING_BIT): Define.
	* libsupc++/guard.cc: Include climits and syscall.h.
	(_GLIBCXX_USE_FUTEX): Define if futex syscall and atomic builtins
	are supported.
	(_GLIBCXX_FUTEX_WAIT, _GLIBCXX_FUTEX_WAKE): Likewise.
	(__guard_test_bit): New static inline.
	(__cxa_guard_acquire, __cxa_guard_release, __cxa_guard_abort): Use
	atomic builtins and futex syscall if _GLIBCXX_USE_FUTEX.
config/
	* futex.m4: New file.
libgomp/
	* configure.ac: Move futex checking into ../config/futex.m4.
	* configure: Rebuilt.
	* aclocal.m4: Rebuilt.
	* Makefile.in: Rebuilt.

	* configure.tgt: Rename have_tls to gcc_cv_have_tls to match
	2007-10-15 ../config/tls.m4 change.

From-SVN: r131399