Oh right! Thanks.
But now I'm getting a different error:
checking for libmemcached location... configure: error: memcached support requires libmemcached. Use --with-libmemcached-dir=<DIR> to specify the prefix where libmemcached headers and library are located
memcached installed libmemcached10 as dependency, I don't see why it's not detecting the files...
Ok I just found the additional package:
yum install libmemcached10-devel