Preserve ordering between -include and -include-pth.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67354 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Driver/clang.cpp b/Driver/clang.cpp
index 31aedbf..1fd54d4 100644
--- a/Driver/clang.cpp
+++ b/Driver/clang.cpp
@@ -934,7 +934,8 @@
   // Add implicit #includes from -include and -include-pth.
   bool handledPTH = ImplicitIncludePTH.empty();
   for (unsigned i = 0, e = ImplicitIncludes.size(); i != e; ++i) {
-    if (!handledPTH) {
+    if (!handledPTH &&
+        ImplicitIncludePTH.getPosition() < ImplicitIncludes.getPosition(i)) {
       AddImplicitIncludePTH(PredefineBuffer, PP);
       handledPTH = true;
     }