[PRQ#51000] Deletion Request for mingw-w64-fann

MarsSeed [1] filed a deletion request for mingw-w64-fann [2]: Unused library. Also, last release was in 2013. Not beneficial to keep on AUR. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/mingw-w64-fann/