mysql: update to 5.5.27 and finally switch to systemd.

srcpkgs/mysql/files/mysqld-post

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+while true; do
+	response=`/usr/bin/mysqladmin -uUNKNOWN_USER ping 2>&1` && break
+	echo "$response" | grep -q "mysqld is alive" && break
+	sleep 1
+done