Bring in 'CHAR_BIT' for GCC 4.3.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64196 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 1d59489..6f8a214 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Bitcode/SerializationFwd.h"
+#include <climits>
 using llvm::isa;
 using llvm::cast;
 using llvm::cast_or_null;