[PRQ#49424] Deletion Request for libshm_arena

MarsSeed [1] filed a deletion request for libshm_arena [2]: Unneeded, discontinued library, release candidate version, from 2014. [a] No upstream development since that year. [b] Not used on AUR, so it's not beneficial to keep. [a]: https://sourceforge.net/projects/shm-arena/files/ [b]: https://sourceforge.net/p/shm-arena/code/HEAD/tree/ [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/libshm_arena/