growl: fix memleak.

(cherry picked from commit 37e54c44)
Signed-off-by: Rémi Duraffort <ivoire@videolan.org>

modules/misc/notify/growl.m

@@ -222,6 +222,7 @@ static int ItemChange( vlc_object_t *p_this, const char *psz_var,
     NotifyToGrowl( p_intf, psz_tmp, art );
 
     if( art ) CFRelease( art );
+    free( psz_tmp );
 
     vlc_object_release( p_input );
     return VLC_SUCCESS;