libstdc++: Ignore deprecated warnings [PR104037]

The std::pointer_to_binary_function utility was deprecated in C++11 and
removed in C++17. Libstdc++ has started to warn about using it, so
suppress the warnings for this test.

gcc/testsuite/ChangeLog:

	PR testsuite/104037
	* g++.old-deja/g++.robertl/eb43.C: Ad -Wno-deprecated.