Add snappy

cmake -D DEP_VERSION=1.1.1-cb1 ../../build/cbdeps/snappy

Change-Id: I3e291c25218ce0b712602890e14b35c2dec20941
Reviewed-on: http://review.couchbase.org/44555
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>