Fix pr81192.c for int16 targets

I had missed when converting this
testcase to Gimple that there was a define
for int/unsigned type specifically to get
an INT32 type. This means when using a
literal integer constant you need to use the
`_Literal (type)` to form the types correctly on the
constants.

This fixes the issue and has been both tested on
xstormy16-elf and x86_64-linux-gnu.

Committed as obvious.

gcc/testsuite/ChangeLog:

	PR testsuite/109776
	* gcc.dg/pr81192.c: Fix integer constants for int16 targets.