don't leak run buffer in wincleartag

Reference: /n/atom/patch/applied2013/acmetagleak
Date: Wed Dec  4 23:27:34 CET 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/acme/wind.c	Wed Dec  4 23:27:19 2013
+++ /sys/src/cmd/acme/wind.c	Wed Dec  4 23:27:19 2013
@@ -328,8 +328,10 @@
 	for(; i<n; i++)
 		if(r[i] == '|')
 			break;
-	if(i == n)
+	if(i == n){
+		free(r);
 		return;
+	}
 	i++;
 	textdelete(&w->tag, i, n, TRUE);
 	free(r);