x11-wm/jwm: Update to 2.3.6

• Update LICENSE deatils to MIT, as per upstream change
• Add LIB_DEPENDS on print/freetype2: as detected by stage-qa, for XFT option

Approved by: adamw (mentor)
Relnotes: http://joewing.net/projects/jwm/release-2.3.shtml#v2.3.6
Differential Revision: https://reviews.freebsd.org/D7596