Add cctype include.

This appears to leak in already on libc++ platforms, but is breaking on
some other targets.

llvm-svn: 332955
diff --git a/clang/lib/CodeGen/CGObjCGNU.cpp b/clang/lib/CodeGen/CGObjCGNU.cpp
index 78029da..eb01659 100644
--- a/clang/lib/CodeGen/CGObjCGNU.cpp
+++ b/clang/lib/CodeGen/CGObjCGNU.cpp
@@ -35,6 +35,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ConvertUTF.h"
+#include <cctype>
 
 using namespace clang;
 using namespace CodeGen;