Re: binutils: Add a test for strip with build notes

The new test wasn't being run, and failed due to relocations against
.gnu.build.attributes being stripped by default strip behaviour.
We probably should be keeping these relocations, but I haven't made
that change here.
BTW, the new test fails on ia64-hpux but that's just a repeat of the
existing note-5 fail.

	PR 31999
	* testsuite/binutils-all/strip-16.d: strip with --strip-unneeded
	and --merge-notes.
	* testsuite/binutils-all/objcopy.exp: Run the new test.  Sort
	other strip tests.