re PR c++/14808 ([win32] Undefined results with virtual base classes)

re PR c++/14808 ([win32] Undefined results with virtual base classes)

	PR c++/14808
	* defaults.h (TARGET_USE_LOCAL_THUNK_ALIAS_P): New macro. Default
	to 1 if ASM_OUTPUT_DEF is defined.
	* doc/tm.texi (TARGET_USE_LOCAL_THUNK_ALIAS_P): Document.
	* config/i386/cygming.h (TARGET_USE_LOCAL_THUNK_ALIAS_P): Define.
	Set to non-zero iff not a one_only decl.

	* cp/method.c (use_thunk): Test TARGET_USE_LOCAL_THUNK_ALIAS_P rather
	than ASM_OUTPUT_DEF.

From-SVN: r80525