krb5: fix memory leak in krb_auth

The FTP command allocated by aprintf() must be freed after usage.

Reviewed-by: Daniel Stenberg <daniel@haxx.se>

lib/krb5.c

@@ -265,6 +265,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
           result = CURLE_OUT_OF_MEMORY;
 
         free(p);
+        free(cmd);
 
         if(result) {
           ret = -2;