* c-common.c (c_common_reswords): Add _Static_assert for C.
	* c-parser.c (c_token_starts_declaration,
	c_parser_next_token_starts_declaration,
	c_parser_static_assert_declaration_no_semi,
	c_parser_static_assert_declaration): New.
	(c_parser_declaration_or_fndef): Add parameter static_assert_ok.
	Handle static assertions if static_assert_ok.
	(c_parser_external_declaration, c_parser_declaration_or_fndef,
	c_parser_compound_statement_nostart, c_parser_label,
	c_parser_for_statement, c_parser_objc_methodprotolist,
	c_parser_omp_for_loop): All callers of
	c_parser_declaration_or_fndef changed.
	(c_parser_struct_declaration): Handle static assertions.
	(c_parser_compound_statement_nostart): Use
	c_parser_next_token_starts_declaration and
	c_token_starts_declaration to detect start of declarations.
	(c_parser_label, c_parser_for_statement, c_parser_omp_for_loop):
	Likewise.

testsuite:
	* gcc.dg/c1x-static-assert-1.c, gcc.dg/c1x-static-assert-2.c,
	gcc.dg/c1x-static-assert-3.c, gcc.dg/c1x-static-assert-4.c,
	gcc.dg/c1x-static-assert-5.c, gcc.dg/c1x-static-assert-6.c,
	gcc.dg/c90-static-assert-1.c, gcc.dg/c99-static-assert-1.c: New
	tests.

From-SVN: r159459