* g++.dg/ext/dllexport-MI1.C: Enable for x86_64 mingw
	and adjust -export symbol scanning.
	* g++.dg/ext/dllexport1.C: Likewise.
	* g++.dg/ext/dllexport3.C: Likewise.
	* gcc.dg/dll-3.c: Likewise.
	* gcc.dg/dll-4.c: Likewise.
	* gcc.dg/dll-5.c: Likewise.

From-SVN: r165261