MFC r312467:

Use SRCTOP-relative paths and .CURDIR with :H instead of ".." specified paths

This implifies pathing in make/displayed output

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Enable ncurses wide character support

Approved by: delphij (mentor)
Tested by: kris on pointyhat (early version), current@