Fix this file to have the necessary standard library includes and use
the `std::` namespace. Should fix a number of build bots as well.

llvm-svn: 340721
diff --git a/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp b/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp
index 039b122..0e0b01d 100644
--- a/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangleNodes.cpp
@@ -12,9 +12,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "MicrosoftDemangleNodes.h"
-
 #include "llvm/Demangle/Compiler.h"
 #include "llvm/Demangle/Utility.h"
+#include <cctype>
 
 using namespace llvm;
 using namespace ms_demangle;
@@ -30,7 +30,7 @@
     return;
 
   char C = OS.back();
-  if (isalnum(C) || C == '>')
+  if (std::isalnum(C) || C == '>')
     OS << " ";
 }