Implement noexcept operator (5.3.7)

Implement noexcept operator (5.3.7)

	Implement noexcept operator (5.3.7)
	* c-common.c (c_common_reswords): Add noexcept.
	* c-common.h (enum rid): Add RID_NOEXCEPT.
cp/
	* cp-tree.def (NOEXCEPT_EXPR): New.
	* except.c (check_noexcept_r, finish_noexcept_expr): New.
	* cp-tree.h: Declare finish_noexcept_expr.
	* parser.c (cp_parser_unary_expression): Parse noexcept-expression.
	* pt.c (tsubst_copy_and_build): And tsubst it.
	(type_dependent_expression_p): Handle it.
	(value_dependent_expression_p): Handle it.

From-SVN: r160297