Workaround for libtinfo detection on Slackware64 14.2, solves #4362. (#4434)
Workaround for libtinfo detection on Slackware64 14.2, solves #4362. (#4434)

* Workaround for libtinfo detection on Slackware64 14.2

Expanded the already present workaround for finding libtinfo on Arch linux when `ldconfig -p` doesn't find it to also work in 64 bit Slackware.
Basically also searches the directory `/usr/lib64/` in addition to `/usr/lib/` for libtinfo or ncurses libraries (see #4362).

* rewrite of the slackware64 'ldconfig -p' workaround as per suggestions in pr #4434

* make the slackware64 'ldconfig -p' workaround build on windows

juhp/stack,juhp/stack