Change the way KEYNOMS is defined to be more comprehensible. 

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160663 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index 96d09a6..92cc179 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -103,8 +103,8 @@
     KEYOPENCL = 0x200,
     KEYC11 = 0x400,
     KEYARC = 0x800,
-    KEYALL = 0x0fff,
-    KEYNOMS = 0x1000
+    KEYNOMS = 0x01000,
+    KEYALL = (0xffff & ~KEYNOMS) // Because KEYNOMS is used to exclude.
   };
 }