Driver: Fix spurious warning (from -cc1) about unused -fapple-kext on C inputs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124875 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/Tools.cpp

@@ -1358,7 +1358,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // these by hand.
 
   if (Args.hasArg(options::OPT_mkernel)) {
-    if (!Args.hasArg(options::OPT_fapple_kext))
+    if (!Args.hasArg(options::OPT_fapple_kext) && types::isCXX(InputType))
       CmdArgs.push_back("-fapple-kext");
     if (!Args.hasArg(options::OPT_fbuiltin))
       CmdArgs.push_back("-fno-builtin");