Fix build on PHP 7+.
Also fix dependancies on PHP 5.6 (mysqli not mysql for all PHP versions now).
Update Makefile to remove all portlint warnings.
Add flavour support.

PR: 227375
Submitted by: freebsd-ports@dan.me.uk
Reported by: freebsd-ports@dan.me.uk
Reviewed by: mfechner@FreeBSD.org
Approved by: mentors (implicit)