common.opt: New option -fstack-protector-explicit.

2015-01-14  Marcos Diaz <marcos.diaz@tallertechnologies.com>

	* common.opt: New option -fstack-protector-explicit.
	* cfgexpand.c (SPCT_FLAG_EXPLICIT): New enum.
	(stack_protect_decl_phase): Handle stack_protect attribute for
	explicit stack protection requests.
	(expand_used_vars): Similarly.
	* doc/cpp.texi (__SSP_EXPLICIT__): Document predefined macro.
	* doc/extend.texi: Add documentation for "stack_protect" attribute.
	* doc/invoke.texi: Add documentation for -fstack-protector-explicit.

	* c-cppbuiltin.c (c_cpp_builtins): New cpp define __SSP_EXPLICIT__
	for the new option fstack-protector_explicit.
	* c-common.c (c_common_attribute_table): Add stack_protect attribute.
	(handle_stack_protect_attribute): New function.

	* gcc.dg/stackprotectexplicit1.c: New test.
	* g++.dg/stackprotectexplicit2.c: New test.

From-SVN: r219633