s390: Fix builtin-classify-type-1.c on s390 too [PR112725]

s390 suffers from the same issue with __builtin_classify_type vector
arguments, the target hook diagnoses those because it thinks a vector
is passed to an unprototyped function, but in this case it is a type-generic
builtin which can support vector types just fine, by folding into the
appropriate constant.

This fixes
-FAIL: c-c++-common/builtin-classify-type-1.c  -Wc++-compat  (test for excess errors)
-UNRESOLVED: c-c++-common/builtin-classify-type-1.c  -Wc++-compat  compilation failed to produce executable
on s390x-linux.

2023-12-01  Jakub Jelinek  <jakub@redhat.com>

	PR target/112725
	* config/s390/s390.cc (s390_invalid_arg_for_unprototyped_fn): Return
	NULL for __builtin_classify_type calls with vector arguments.