re PR c++/11788 (missing implicit instantiation of static member function)

cp:
	PR c++/11788
	* typeck.c (build_address): If it is a function, mark it used.
	(build_unary_op): Do not lose object's side-effects when taking
	address of static member function.
	* class.c (resolve_address_of_overloaded_function): Use
	tsubst_flags_t parameter. Only expect overload sets. Adjust.
	(instantiate_type): Adjust flags passing. Do not lose object's
	side-effects when taking address of static member function.
testsuite:
	PR c++/11788
	* g++.dg/overload/addr1.C: New test.

From-SVN: r71304