testsuite: Add -Wno-psabi to pr104505.c

The testcase references a vector type that elicits a psabi warning.
This patch adds the option to suppress the warning.

	* c-c++-common/pr104505.c: Add -Wno-psabi.

gcc/testsuite/c-c++-common/pr104505.c

 /* { dg-do compile } */
+/* { dg-additional-options "-Wno-psabi" } */
 
 typedef char __attribute__((__vector_size__ (8))) U;
 typedef short __attribute__((__vector_size__ (16))) V;