try to fix MSVC build




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147198 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/TableGen/TGLexer.cpp b/lib/TableGen/TGLexer.cpp
index 0977b00..c9c674c 100644
--- a/lib/TableGen/TGLexer.cpp
+++ b/lib/TableGen/TGLexer.cpp
@@ -22,6 +22,9 @@
 #include <cstdlib>
 #include <cstring>
 #include <cerrno>
+
+#include "llvm/Config/config.h"
+
 using namespace llvm;
 
 TGLexer::TGLexer(SourceMgr &SM) : SrcMgr(SM) {