fixed small error in types in sql/field.cc

(char * -> const char*)


sql/field.cc:
  fixed small error in types (char * -> const char*)

sql/field.cc

@@ -4721,7 +4721,7 @@ String *Field_enum::val_str(String *val_buffer __attribute__((unused)),
 {
   uint tmp=(uint) Field_enum::val_int();
   if (!tmp || tmp > typelib->count)
-    val_ptr->set((char*)"",0);
+    val_ptr->set((const char*)"",0);
   else
     val_ptr->set((const char*) typelib->type_names[tmp-1],
 		 (uint) strlen(typelib->type_names[tmp-1]));