testsuite: Improve g++.dg/ext/attr-parm-1.C testcase [PR94946]

testsuite: Improve g++.dg/ext/attr-parm-1.C testcase [PR94946]

The testcase in the current form doesn't FAIL without the patch on
x86_64-linux unless also testing with -m32; as that the 64-bit testing
on that target is probably way more common, and we can use also attributes
that FAIL without the patch with -m64, the following patch adjusts the
test, so that it FAILs without the patch for both -m64 and -m32 (but not
-mx32) and PASSes with the patch.

2020-05-07  Jakub Jelinek  <jakub@redhat.com>

	PR c++/94946
	* g++.dg/ext/attr-parm-1.C: Enable the test also for lp64 x86, use
	sysv_abi and ms_abi attributes in that case instead of fastcall and
	no attribute.