Remove the storage for -cxx-system-include. Make libcxx toolchain
use -nostdinc++ and -cxx-isystem.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126223 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChain.cpp b/lib/Driver/ToolChain.cpp
index e4051a1..e305683 100644
--- a/lib/Driver/ToolChain.cpp
+++ b/lib/Driver/ToolChain.cpp
@@ -198,7 +198,8 @@
 
   switch (Type) {
   case ToolChain::CST_Libcxx:
-    CmdArgs.push_back("-cxx-system-include");
+    CmdArgs.push_back("-nostdinc++");
+    CmdArgs.push_back("-cxx-isystem");
     CmdArgs.push_back("/usr/include/c++/v1");
     break;