Moved here from LLVM Clang's configuration options and related macros.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124825 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
index 7fa7d01..d681033 100644
--- a/lib/Frontend/InitHeaderSearch.cpp
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -11,6 +11,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifdef HAVE_CLANG_CONFIG_H
+# include "clang/Config/config.h"
+#endif
+
 #include "clang/Frontend/Utils.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/LangOptions.h"