testsuite: Fix up pr98807.c on i686-linux [PR98807]

The new testcase FAILs on i686-linux with:
gcc/testsuite/gcc.dg/pr98807.c: In function 'foo0':
gcc/testsuite/gcc.dg/pr98807.c:20:1: warning: SSE vector return without SSE enabled changes the ABI [-Wpsabi]
gcc/testsuite/gcc.dg/pr98807.c:19:1: note: the ABI for passing parameters with 16-byte alignment has changed in GCC 4.6
gcc/testsuite/gcc.dg/pr98807.c:19:1: warning: SSE vector argument without SSE enabled changes the ABI [-Wpsabi]
FAIL: gcc.dg/pr98807.c (test for excess errors)

Adding usual testcase treatment for such cases.

2021-01-26  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/98807
	* gcc.dg/pr98807.c: Add -Wno-psabi -w to dg-options.