MarsSeed [1] filed a deletion request for libstdc++296 [2]: Please delete. Missing source, and it's an unmaintained duplicate of AUR/libstdc++296-bin (yes, both packages extract prebuilt binaries, so even this one's name is wrong). Safe to delete, no deleterious impact whatsoever.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/libstdc++296/
