src: fix MallocedBuffer move assignment operator

PR-URL: #20883
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

src/util.h

@@ -438,7 +438,7 @@ struct MallocedBuffer {
   }
   MallocedBuffer& operator=(MallocedBuffer&& other) {
     this->~MallocedBuffer();
-    return *new(this) MallocedBuffer(other);
+    return *new(this) MallocedBuffer(std::move(other));
   }
   ~MallocedBuffer() {
     free(data);