re PR c++/83918 ([c++17] ICE on constexpr eval of datatype involving function and variadic template)

	PR c++/83918
	* tree.c (maybe_wrap_with_location): Use NON_LVALUE_EXPR rather than
	VIEW_CONVERT_EXPR to wrap CONST_DECLs.

	* g++.dg/cpp1z/pr83918.C: New test.

From-SVN: r256972