Fix typo in comment.

Masahiko Sawada

Discussion: http://postgr.es/m/CAD21AoDrf5AOpZ-mX-j6O=zFNFfKaTdHkv3o1X2eSs2nBXALug@mail.gmail.com

src/backend/storage/ipc/dsm_impl.c

@@ -682,7 +682,7 @@ dsm_impl_windows(dsm_op op, dsm_handle handle, Size request_size,
 
 	/*
 	 * Handle teardown cases.  Since Windows automatically destroys the object
-	 * when no references reamin, we can treat it the same as detach.
+	 * when no references remain, we can treat it the same as detach.
 	 */
 	if (op == DSM_OP_DETACH || op == DSM_OP_DESTROY)
 	{