databases/couchdb: update to 1.7.1 incl critical security fixes

• addresses 2 critical security fixes listed below
• includes fix for post-1.7.0 /_all_docs returning 500 for DB members

Reviewed by: olgeni (maintainer)
Approved by: jrm (mentor)
MFH: 2017Q4
Security: CVE-2017-12635
Security: CVE-2017-12636
Security: https://lists.apache.org/thread.html/6c405bf3f8358e6314076be9f48c89a2e0ddf00539906291ebdf0c67@%3Cdev.couchdb.apache.org%3E
Sponsored by: http://iwantmyname.com/
Differential Revision: https://reviews.freebsd.org/D13076