Revert "5.6.2"

This reverts commit f8a26e7c0d28c7569769007ac91f70434f07e0a7.
Revert "add libmemcached"

This reverts commit 820bfe8ce1b5fd293d6fa0f2c40f0c9818a35c44.
Revert "add memcached"

This reverts commit 7a0ecf7a0c1535c4f49c737388bf005b94831225.