re PR c++/68475 (ICE: in merge_exception_specifiers, at cp/typeck2.c:2115 with -fno-exceptions on invalid code)

	PR c++/68475
	* decl.c (check_redeclaration_exception_specification): Check
	regardless of -fno-exceptions.
	* typeck2.c (merge_exception_specifiers): Relax assert by checking
	flag_exceptions too.

	* g++.dg/g++.dg/cpp0x/noexcept29.C: New.

From-SVN: r234667