Use pkg-config for getting libmemcached CFLAGS/LIBS
Use pkg-config for getting libmemcached CFLAGS/LIBS

Also, require version 1.0 or later of libmemcached.
This is because older versions of libmemcached have
a different API and because we have stability issues
with version 0.31 on CentOS 6.5.

dcrossleyau/yaz,dcrossleyau/yaz,dcrossleyau/yaz