c++: -Waddress and value-dependent expr [PR105885]

c++: -Waddress and value-dependent expr [PR105885]

We already suppress various warnings for code that would be tautological if
written directly, but not when it's the result of template substitution.  It
seems we need to do this for -Waddress as well.

	PR c++/105885

gcc/cp/ChangeLog:

	* pt.cc (tsubst_copy_and_build): Also suppress -Waddress for
	comparison of dependent operands.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/constexpr-if37.C: New test.