[history-substring-search] Only load terminfo feature of zsh/terminfo
[history-substring-search] Only load terminfo feature of zsh/terminfo

like we did for the input module in 7861145, and to make modules
independent of each other, as discussed in #261.

Eriner/zim,joshuarubin/dotfiles,joshuarubin/dotfiles,joshuarubin/dotfiles,joshuarubin/dotfiles