c++: Avoid duplicate diagnostic calling unavailable function [PR109177]

c++: Avoid duplicate diagnostic calling unavailable function [PR109177]

As the PR shows, we currently emit duplicate diagnostics for calls to
functions marked with __attribute__((unavailable)). This patch fixes
that.

gcc/cp/ChangeLog:

	PR c++/109177
	* call.cc (build_over_call): Use make_temp_override to suppress
	both unavailable and deprecated warnings when calling
	build_addr_func.

gcc/testsuite/ChangeLog:

	PR c++/109177
	* g++.dg/ext/pr109177.C: New test.