PR tree-optimization/34036

	PR tree-optimization/34036
	* opts.c (set_fast_math_flags): Do not set flags in common
	with set_unsafe_math_optimizations_flags, invoke it directly.
	(set_unsafe_math_optimizations_flags): Unset flag_trapping_math
	and flag_signed_zeros.
	* toplev.c (process_options): Force flag_associative_math to 0 and
	warn, if it is set and either flag_trapping_math or flag_signed_zeros
	is set too.
	* doc/invoke.texi (Optimize Options): Document the new behavior
	of -funsafe-math-optimizations, that -fassociative-math requires
	both -fno-signed-zeros and -fno-trapping-math and make it clear
	that -fno-trapping-math requires -fno-signaling-nans.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@130286 138bc75d-0d04-0410-961f-82ee72b054a4