Add const to operator

Author: jlatusek

src/credentials/GroupDataProvider.h

@@ -72,7 +72,7 @@ class GroupDataProvider
                 Platform::CopyString(name, groupName);
             }
         }
-        bool operator==(const GroupInfo & other)
+        bool operator==(const GroupInfo & other) const
         {
             return (this->group_id == other.group_id) && !strncmp(this->name, other.name, kGroupNameMax);
         }