fix a clang warning
diff --git a/tinyxml2.cpp b/tinyxml2.cpp
index 0dc5cd4..0289a13 100755
--- a/tinyxml2.cpp
+++ b/tinyxml2.cpp
@@ -1967,9 +1967,9 @@
             _entityFlag[ (int)entities[i].value ] = true;

         }

     }

-    _restrictedEntityFlag['&'] = true;

-    _restrictedEntityFlag['<'] = true;

-    _restrictedEntityFlag['>'] = true;	// not required, but consistency is nice

+    _restrictedEntityFlag[(int)'&'] = true;

+    _restrictedEntityFlag[(int)'<'] = true;

+    _restrictedEntityFlag[(int)'>'] = true;	// not required, but consistency is nice

     _buffer.Push( 0 );

 }