Fix mail/qpopper:

• remove MASTER_SITE ftp.qualcomm.com that is no more and add a couple of living distfile sources;

• describe custom BSD-style Quallcom license for the distfile;

• fix building with openssl-1.1.1 that no longer has SSLv2 support plus made struct ssl_st (SSL) completely opaque, so better use public interface SSL_session_reused() instead of direct access to now hidden "hit" part of struct; this works for previous openssl versions too.

No PORTREVISION bump as this fixed package building for FreeBSD 12+
and has no visible package changes for other supported branches.

PR: 232383
Reported by: sbruno
Approved by: bc979@lafn.org (maintainer timeout, 4 weeks)