re PR c++/10496 ([diagnostic] erroneus suggestion in diagnostic asks the user to write "&const class::memfun" which is illegal)

	PR c++/10496
	* typeck.c (build_unary_op): Don't output const qualifier when
	output invalid pointer-to-member diagnostics.

	* g++.dg/warn/pmf1.C: New test.

From-SVN: r66481