re PR middle-end/92825 (Unnecesary stack protection in Firefox's LightPixel.)

re PR middle-end/92825 (Unnecesary stack protection in Firefox's LightPixel.)

	PR middle-end/92825
	* cfgexpand.c (add_stack_protection_conflicts): Change return type
	from void to bool, return true if at least one stack_vars[i].decl
	is addressable.
	(record_or_union_type_has_array_p, stack_protect_decl_p): Remove.
	(expand_used_vars): Don't call stack_protect_decl_p, instead for
	-fstack-protector-strong set gen_stack_protect_signal to true
	if add_stack_protection_conflicts returned true.  Formatting fixes.
	* doc/invoke.texi (-fstack-protector-strong): Clarify that optimized
	out variables or variables not living on the stack don't count.
	(-fstack-protector): Likewise.  Clarify it affects >= 8 byte arrays
	rather than > 8 byte.

	* gcc.target/i386/pr92825.c: New test.

From-SVN: r279193