Add missing include for Linux buildbot

llvm-svn: 160971
diff --git a/clang/tools/libclang/CXComment.cpp b/clang/tools/libclang/CXComment.cpp
index 4189b31..05dc6fe 100644
--- a/clang/tools/libclang/CXComment.cpp
+++ b/clang/tools/libclang/CXComment.cpp
@@ -20,6 +20,8 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 
+#include <climits>
+
 using namespace clang;
 using namespace clang::cxstring;
 using namespace clang::comments;