[Darwin, PPC, testsuite] Require stabs support for a test.

The test fails if the assembler doesn't support stabs.

2019-07-13  Iain Sandoe  <iain@sandoe.co.uk>

	* gcc.target/powerpc/stabs-attrib-vect-darwin.c: Require stabs
	support.

From-SVN: r273470

gcc/testsuite/ChangeLog

+2019-07-13  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* gcc.target/powerpc/stabs-attrib-vect-darwin.c: Require stabs
+	support.
+
 2019-07-13  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	PR target/91148

gcc/testsuite/gcc.target/powerpc/stabs-attrib-vect-darwin.c

 /* Test Attribute Vector associated with vector type stabs.  */
 /* { dg-do compile { target powerpc*-*-darwin* } } */
+/* { dg-require-effective-target stabs } */
 /* { dg-options "-gstabs+ -fno-eliminate-unused-debug-types -faltivec" } */
 
 int main ()