x11-terms/alacritty: add terminfo useflag
This will allow skipping compilation and installation of terminfo
definitions has already been upstreamed to ncurses
https://lists.gnu.org/archive/html/bug-ncurses/2018-10/msg00024.html
https://invisible-island.net/ncurses/terminfo.src.html#toc-_Alacritty
so at some point ncurses will get updated we'll be able to avoid
collisions.
Even without terminfo alacritty happily works with TERM=xterm-256color
Package-Manager: Portage-2.3.62, Repoman-2.3.12
Signed-off-by: Georgy Yakovlev <gyakovlev@gentoo.org>