graphics/freeimage: adopt/add pkgconf support
- adopt port
- reorder Makefile (portclippy)
- add pkgconf support
- bump portrevision
PR: 254340
Submitted by: Freddy DISSAUX <dsx@bsdsx.fr>
Approved by: dbaio, garga (mentors)
Differential Revision: https://reviews.freebsd.org/D29311