Fix compilation on platforms that split the ncurses and tinfo libraries

Some platforms compile ncurses in such a way that the tinfo library needs to
be separately linked in (e.g. Gentoo).

The tinfo library is a low-level library being used by and bundled with
ncurses.

Adding '-ltinfo' to WINTTYLIB in the hint files was considered the most robust
solution to this problem.  This still works on systems with ncurses 5.9.
Using pkg-config was ruled out as the default build of ncurses doesn't install
the necessary files.

sys/unix/hints/linux

@@ -47,7 +47,7 @@ WINLIB = $(WINTTYLIB) $(WINCURSESLIB)
 #WINSRC += tile.c
 #WINOBJ += tile.o
 
-WINTTYLIB=-lcurses
+WINTTYLIB=-lncurses -ltinfo
 
 CHOWN=true
 CHGRP=true