2011-01-22 Ivan Maidanski <ivmai@mail.ru> (mostly Jean-Claude Beaudoin)

2011-01-22  Ivan Maidanski  <ivmai@mail.ru> (mostly Jean-Claude Beaudoin)

	* darwin_stop_world.c (GC_FindTopOfStack): Prefix and suffix
	"volatile" keyword with double underscore.
	* mach_dep.c (GETCONTEXT_FPU_EXCMASK_BUG): Recognize new macro and
	include fenv.h if defined (unless NO_GETCONTEXT or HAVE_PUSH_REGS).
	* mach_dep.c (GC_with_callee_saves_pushed): Restore FPU exception
	mask corrupted by getcontext if GETCONTEXT_FPU_EXCMASK_BUG.
	* include/private/gcconfig.h (GETCONTEXT_FPU_EXCMASK_BUG): Define
	for Linux/amd64 (since its GLibc getcontext currently has the bug).