www/piwik: Update from 3.2.0 to 3.2.1
Changelog: https://piwik.org/changelog/piwik-3-2-1/
*While here, switch to DISTVERSION
PR: 224550
Reported by: flo
Approved by: myself (in representation for tz)
Approved by: xxx (mentor)
#Differential Revision: https://reviews.freebsd.org/Dxxxxx