c++: direct enum init from type-dep elt [PR112515]

c++: direct enum init from type-dep elt [PR112515]

The NON_DEPENDENT_EXPR removal exposed that is_direct_enum_init can be
called in a template context on a CONSTRUCTOR that isn't type-dependent
but whose element is.

	PR c++/112515

gcc/cp/ChangeLog:

	* decl.cc (is_direct_enum_init): Check type-dependence of the
	single element.

gcc/testsuite/ChangeLog:

	* g++.dg/template/non-dependent30.C: New test.