Driver: -mkernel and -fapple-kext imply -mno-red-zone.

llvm-svn: 70010
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 8393e9c..8ff8197 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -307,7 +307,9 @@
       CmdArgs.push_back("--unwind-tables=0");
     if (!Args.hasFlag(options::OPT_mred_zone,
                       options::OPT_mno_red_zone,
-                      true))
+                      true) ||
+        Args.hasArg(options::OPT_mkernel) ||
+        Args.hasArg(options::OPT_fapple_kext))
       CmdArgs.push_back("--disable-red-zone");
     if (Args.hasFlag(options::OPT_msoft_float,
                      options::OPT_mno_soft_float,