Fix broken buildbots because of r288424 (NFC).

EugeneZelenko · EugeneZelenko · commit e7c0b2e0f81a · 2016-12-01T22:26:55.000Z
llvm-svn: 288426
diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
@@ -31,6 +31,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ManagedStatic.h"
 #include <cassert>
+#include <climits>
 #include <cstddef>
 #include <initializer_list>
 #include <string>
