- Add ncurses patch 20210130
+ correct an off-by-one in comparison in waddch_literal() which caused
scrolling when a double-cell character would not fit at the lower
right corner of the screen (report by Benno Schulenberg).
+ split-out att610+cvis, vt220+cvis, vt220+cvis8 -TD
+ add vt220-base, for terminal emulators which generally have not
supported att610's blinking cursor control -TD
+ use vt220+cvis in vt220, etc -TD
+ use att610+cvis, xterm+tmux and ansi+enq in kitty -TD
+ use vt220+cvis in st, terminology, termite since they ignore
blinking-cursor detail in att610+cvis -TD
- Port patch ncurses-6.2.dif
* Skip cvvis entries where vt220+cvis is used
* Skip function keys in rxvt-basic as rxvt+pcfkeys and use=vt220+keypadcw
is used

- Add ncurses patch 20210123
+ modify package/config scripts to provide an explicit -L option for
cases when the loader search path has other directories preceding
the one in which ncurses is installed (report by Yuri Victorovich).
+ minor build-fixes in configure script and makefiles to work around
quirks of pmake.