math/py-matplotlib: Update to 2.1.2

Maintainer's timeout expired: mainland@apeiron.net

Additional port changes:

• Changed to DISTVERSION
• Changed WWW to https URL

PR: 222689
Submitted by: Kostas Oikonomou <ko@research.att.com> (version 2.0.2)
Approved by: portmgr (maintainer timeout, 14 days)
Approved by: tcberner (mentor, implicit)