c++: Template template parameter in constraint [PR95371]

c++: Template template parameter in constraint [PR95371]

any_template_parm_r was assuming that the DECL_TEMPLATE_RESULT of a template
will have a suitable TEMPLATE_INFO from which we can look at the generic
arguments for that template.  But that wasn't true for a template template
parameter; this patch makes it so.

gcc/cp/ChangeLog:

	PR c++/95371
	* pt.c (process_template_parm): Set DECL_TEMPLATE_INFO
	on the DECL_TEMPLATE_RESULT.

gcc/testsuite/ChangeLog:

	PR c++/95371
	* g++.dg/cpp2a/concepts-ttp1.C: New test.