mail/qmailmrtg7: Resurrect port

• Update MASTER_SITES to working download location
• Reformat Makefile according to portclippy/portfmt
• For now, ale@ will remain the MAINTAINER

PR: 251953
Reported by: Charles Lecklider <freebsd@charles.lecklider.org>
Reviewed by: osa (mentor)
Approved by: osa (mentor)
Differential Revision: https://reviews.freebsd.org/D28138