Adding missing directive for Power9.

There is currently no codegen for Power9 that depends on the directive
so this is NFC for now but will be important in the future. This was
missed in r268950 so I'm adding it now.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281473 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPC.td

@@ -203,7 +203,7 @@ def ProcessorFeatures {
   list<SubtargetFeature> Power8FeatureList =
       !listconcat(Power7FeatureList, Power8SpecificFeatures);
   list<SubtargetFeature> Power9SpecificFeatures =
-      [FeatureP9Altivec, FeatureP9Vector, FeatureISA3_0];
+      [DirectivePwr9, FeatureP9Altivec, FeatureP9Vector, FeatureISA3_0];
   list<SubtargetFeature> Power9FeatureList =
       !listconcat(Power8FeatureList, Power9SpecificFeatures);
 }