Try to unbreak the C++11 build

Cannot use negative numbers in case statements without running afoul of -Wc++11-narrowing.

llvm-svn: 202455
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCPredicates.h b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCPredicates.h
index c140973..10e328a 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCPredicates.h
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCPredicates.h
@@ -52,8 +52,8 @@
 
     // When dealing with individual condition-register bits, we have simple set
     // and unset predicates.
-    PRED_BIT_SET =   -1,
-    PRED_BIT_UNSET = -2
+    PRED_BIT_SET =   1024,
+    PRED_BIT_UNSET = 1025
   };
   
   /// Invert the specified predicate.  != -> ==, < -> >=.