Fix PLIST

• Fix GH_TAGNAME
• While I'm here, use = instead of += for MAKE_ENV
• Bump PORTREVISION for package change

Reference: http://package23.nyi.freebsd.org/data/110i386-default-PR220605/2017-07-10_18h05m10s/logs/errors/libfastcommon-1.0.36.log
Approved by: portmgr (blanket)