testsuite: Fix PR108080 testcase for some targets [PR121396]

testsuite: Fix PR108080 testcase for some targets [PR121396]

I added a testcase for the (temporary) warning that we don't currently
support the 'gnu::optimize' or 'gnu::target' attributes in r15-10183;
however, some targets produce target nodes even when only an optimize
attribute is present.  This adjusts the warning.

	PR c++/108080
	PR c++/121396

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr108080.H: Also allow target warnings.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
(cherry picked from commit 82e4932623e57ded0f9303621fe329ee5aaba508)