[Darwin, PPC, testsuite] Fix builtins-2 for Darwin.

This cannot pass for current Darwin, since it requires VSX and we
don't have any hardware supporting that.  Add a dg-requires clause
for this.

2019-06-23  Iain Sandoe  <iain@sandoe.co.uk>

	* gcc.target/powerpc/builtins-2.c: Require VSX hardware support.

From-SVN: r272606

gcc/testsuite/ChangeLog

 2019-06-23  Iain Sandoe  <iain@sandoe.co.uk>
 
+	* gcc.target/powerpc/builtins-2.c: Require VSX hardware support.
+
+2019-06-23  Iain Sandoe  <iain@sandoe.co.uk>
+
 	* gcc.target/powerpc/pr80125.c (foo): Use an unsigned char
 	vector explicitly for the vec_perm.
 

gcc/testsuite/gcc.target/powerpc/builtins-2.c

 /* { dg-do run { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target vsx_hw } */
 /* { dg-options "-mdejagnu-cpu=power8 " } */
 
 #include <altivec.h>