Fix pr116588.c for -m32

This is a simple fix which adds the target supports requirement of int128
to the testcase too.

Pushed as obvious after testing to make sure the testcase is UNSUPPORTED now
with -m32 but working with -m64 on x86_64-linux-gnu.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr116588.c: Require int128.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>