For non-Darwin, a plain 'char' type is unsigned.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131967 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index fd59ebb..b959459 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -429,6 +429,7 @@
   default:
     return true;
 
+  case llvm::Triple::arm:
   case llvm::Triple::ppc:
   case llvm::Triple::ppc64:
     if (Triple.getOS() == llvm::Triple::Darwin)