net-p2p/transmission: Refine flavors, port fixes
*Fixes flavor conflicts in Bug 273841
*Patches to build with libfmt>=10.0. Bug 273887
*Adds log-location and log-level options. Bug 269392
*Fixes build errors arising from pkg-plist issues. Bug 273836
See UPDATING for additional information on the usage of flavors.
PR: 273841, 273887, 269392, 273836
Reported by: Benjamin Takacs <nimaje+fbz@bureaucracy.de>
Reported by: diizzy, dereckson@gmail.com
Reported by: Igor Pavlov <igor.arabesc.pavlov@gmail.com>