Don't forward -Wenum-conversion to cc1plus.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165532 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index fdc4eb9..462354a 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3606,6 +3606,7 @@
         .Case("duplicate-method-arg", true)
         .Case("dynamic-class-memaccess", true)
         .Case("enum-compare", true)
+        .Case("enum-conversion", true)
         .Case("exit-time-destructors", true)
         .Case("gnu", true)
         .Case("gnu-designator", true)