PR c++/60364 - noreturn after first decl not diagnosed.

PR c++/60364 - noreturn after first decl not diagnosed.

	* attribs.c (get_attribute_namespace): No longer static.
	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
	attributes.
	(attr_noreturn_exclusions): Make it extern.
	* attribs.h (get_attribute_namespace): Declare.
	* tree-inline.c (function_attribute_inlinable_p): Use
	get_attribute_name.

	* c-attribs.c (handle_noreturn_attribute): No longer static.
	* c-common.h (handle_noreturn_attribute, attr_noreturn_exclusions):
	Declare.
	* c-format.c (check_function_format): Use get_attribute_name.

	* decl.c (duplicate_decls): Give an error when a function is
	declared [[noreturn]] after its first declaration.
	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
	attribute as equivalent to GNU's.
	* tree.c (std_attribute_table): Add noreturn.

	* g++.dg/warn/noreturn-8.C: New test.
	* g++.dg/warn/noreturn-9.C: New test.
	* g++.dg/warn/noreturn-10.C: New test.
	* g++.dg/warn/noreturn-11.C: New test.

From-SVN: r272486