_check_ulimit does not handle "unlimited" in couchbase-server.in

[root@8e9ad25db6d9 /]# ulimit -a

core file size          (blocks, -c) unlimited

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 15622

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 1048576

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 8192

cpu time               (seconds, -t) unlimited

max user processes              (-u) unlimited

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited 

[root@8e9ad25db6d9 /]# /opt/couchbase/bin/couchbase-server: line 72: [: unlimited: integer expression expected