Add missing newline (which breaks MSVC build???)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@92522 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Lex/ExternalPreprocessorSource.h

@@ -31,4 +31,4 @@ public:
   
 }
 
-#endif // LLVM_CLANG_LEX_EXTERNAL_PREPROCESSOR_SOURCE_H
+#endif // LLVM_CLANG_LEX_EXTERNAL_PREPROCESSOR_SOURCE_H
\ No newline at end of file