SOLARIS: Look for ncurses in ncurses/ncurses.h

Solaris 11+ has ncurses.h in ncurses/ncurses.h. Look for it there.

Without this, on Solaris 11.1 we will detect libncurses automatically
(because it lives in /usr/lib), but not ncurses.h (since it is in
ncurses/ncurses.h, not ncurses.h). So, we will fall back to curses.h,
but will try to link to libncurses, which, as you might guess, fails
with various undefined symbols.

Change-Id: Ia174e2a3c97318d6db2a48a6098569aede93522c
Reviewed-on: http://gerrit.openafs.org/8874
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>