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.

doc/fixes36.4

@@ -23,6 +23,7 @@ Fixes to Post-3.6.3 Problems that Were Exposed Via git Repository
 
 Platform- and/or Interface-Specific Fixes or Features
 -----------------------------------------------------
+fix compilation on platforms that split the ncurses and tinfo libraries
 
 
 General New Features