Pull up following revision(s) (requested by riastradh in ticket #899):
	lib/libm/arch/i387/fenv.c: revision 1.5
	lib/libm/arch/x86_64/fenv.c: revision 1.3-1.4
Fix amd64 feraiseexcept so that it actually traps.
The call to fwait got lost somewhere along the line; the i387 code has it.
Fix sense of fegetexcept on x86.
Somehow I overlooked this when I fixed feenableexcept and fedisableexcept
last summer.
Ticket 899.