[gcc-7 backport PATCH, rs6000/pr84371] Update butilins-3*.c tests for power9 codegen.

[Will Schmidt]

Hi, 
  This is a backport of the relevant pieces to fix pr84371 (builtins-3.c
fails on Power9) in the gcc-7 branch.

sniff-tested OK on p7,p8,p9.
OK for backport to gcc-7 ?

Thanks,
-Will

[testsuite]

2018-03-02  Will Schmidt  <will_schm...@vnet.ibm.com>

        Backport from trunk.

        PR target/84371
        * gcc.target/powerpc/builtins-3.c: Update dg-options and dg-skip-if
        stanzas.
        * gcc.target/powerpc/builtins-3.p8.c: Add dg-skip-if stanza.
        * gcc.target/powerpc/builtins-3.p9.c: Add dg-skip-if stanza.

---

Index: gcc/testsuite/gcc.target/powerpc/builtins-3-p8.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/builtins-3-p8.c    (revision 258140)
+++ gcc/testsuite/gcc.target/powerpc/builtins-3-p8.c    (working copy)
@@ -1,6 +1,7 @@
 /* { dg-do compile } */
 /* { dg-require-effective-target powerpc_p8vector_ok } */
 /* { dg-options "-mcpu=power8" } */
+/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { 
"-mcpu=power8" } } */
 
 #include <altivec.h>
 
Index: gcc/testsuite/gcc.target/powerpc/builtins-3-p9.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/builtins-3-p9.c    (revision 258140)
+++ gcc/testsuite/gcc.target/powerpc/builtins-3-p9.c    (working copy)
@@ -1,6 +1,7 @@
 /* { dg-do compile } */
 /* { dg-require-effective-target powerpc_p9vector_ok } */
 /* { dg-options "-mcpu=power9" } */
+/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { 
"-mcpu=power9" } } */
 
 #include <altivec.h>
 
Index: gcc/testsuite/gcc.target/powerpc/builtins-3.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/builtins-3.c       (revision 258140)
+++ gcc/testsuite/gcc.target/powerpc/builtins-3.c       (working copy)
@@ -1,6 +1,7 @@
 /* { dg-do compile } */
 /* { dg-require-effective-target powerpc_vsx_ok } */
-/* { dg-options "-maltivec -mvsx" } */
+/* { dg-options "-O2 -mvsx -mcpu=power6" } */
+/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { 
"-mcpu=power6" } } */
 
 #include <altivec.h>