testsuite: i386: Fix g++.target/i386/pr116275-2.C on Solaris/x86

The new g++.target/i386/pr116275-2.C test FAILs on 32-bit Solaris/x86:

FAIL: g++.target/i386/pr116275-2.C   scan-assembler vpslld

This happens because Solaris defaults to -mstackrealign, disabling -mstv.

Fixed by disabling the former and enabling the latter.

Tested on i386-pc-solaris2.11 and x86_64-pc-linux-gnu.

2024-08-20  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc/testsuite:
	* g++.target/i386/pr116275-2.C (dg-options): Add -mstv
	-mno-stackrealign.