databases/couchdb: update 1.7.1 to 1.7.2

• addresses CVE referred to in https://blog.couchdb.org/2018/07/10/cve-2018-8007/

Reviewed by: olgeni
Approved by: jrm
MFH: 2018Q3
Security: CVE-2018-8007
Security: CVE-2017-12636
Security: CVE-2017-12635
Differential Revision: https://reviews.freebsd.org/D16207