Remove PHP-5.2 bits

Change-Id: Ib08be2ece5ee17feb55e0a2c18ad15b73f67304f
Reviewed-on: http://review.couchbase.org/25078
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>