c++: enum in generic lambda in template [PR95317]

c++: enum in generic lambda in template [PR95317]

Here we weren't instantiating the enumerators because the arglist still had
the template parameter for the generic lambda, so looking one up failed.  We
need to instantiate if the non-lambda enclosing scope is non-dependent.

gcc/cp/ChangeLog:

	PR c++/95317
	* pt.c (lookup_template_class_1): Do tsubst_enum when
	tsubsting a generic lambda.

gcc/testsuite/ChangeLog:

	PR c++/95317
	* g++.dg/cpp1y/lambda-generic-enum1.C: New test.