Fix VC++ build errors


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23210 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/SubtargetFeature.cpp b/lib/Target/SubtargetFeature.cpp
index dc3aef2..1583f4e 100644
--- a/lib/Target/SubtargetFeature.cpp
+++ b/lib/Target/SubtargetFeature.cpp
@@ -17,7 +17,7 @@
 #include <algorithm>
 #include <vector>
 #include <cassert>
-
+#include <cctype>
 
 using namespace llvm;