testsuite: Adjust pruning

testsuite: Adjust pruning

Here is the patch to adjust the include-stack pruning messages to also
strip out c++ modules.  The ICE regexp was a little too strict such
that if someone overrides the bug-reporting URL it doesn't trigger.
May as well relax it too.

	gcc/testsuite/
	* lib/prune.exp (prune_gcc_output): Adjust include stack pruning
	for modules.
	(print_ices): Relax regexp.