merge xterm 397.

merge xterm 392.

update for xterm 372.

merge xauth 1.1.1 and xterm 370.

revert previous, do it differently and explain why.

fix the value of STDC_NORETURN

merge xterm 367.

define OPT_SIXEL_GRAPHICS here like everything else, rather than
than Makefile. (OPT_GRAPHICS is already defined here.)

merge xterm-366. this includes the fix for CVE-2021-27135.

(note that testing so far has not revealed this problem on netbsd,
though i have not heard about pkgsrc x11 users.)

update for libXt 1.2.0 const/noreturnification:
- define GCC_* as supported by all our compilers
- mark xt_error as noreturn
- clear the error handler with XtSetErrorHandler(NULL) vs
((XtErrorHandler) 0) which avoids missing noreturn issue

merge xterm 330. remove files we'll build now.

add new generated files.

update for xterm 327.

merge xterm 318.

merge xterm 308.

new generated file for xterm.

merge xterm 303.

Enable 256 colors.

From Piotr Meyer in PR 48380.

enable defines that make xterm able to do UTF-8 if instructed by its
environment to do UTF-8.

That means: "env LC_CTYPE=en_US.UTF-8 xterm" for example will get you
an xterm that will take UTF-8 input and display it correctly, provided it
finds a fitting UTF-8 font.

Note that with this version of xterm, -u8 doesn't actually have an effect
any more, but -lc has.

xterm will record the locale settings it has been started with in the
environment variable XTERM_LOCALE. It is probably a good idea to have
at least the encoding part of LC_CTYPE and XTERM_LOCALE match.

merge xterm 293 xtermcfg.h, and patch fontutils.c to actually work
with our selected set of options (issue between OPT_RENDERFONT and
OPT_SHIFT_FONTS.)

merge xterm 267 xtermcfg.h

Revert part of previous:
OPT_WIDE_CHARS definitely makes a difference with a UTF8 locale.

Update this to the latest xterm import. Fixes:
- cut bug where, we could cut only up to 1K before
- disable toolbar by default
- don't assume we've installed luit from pkgsrc
- no opt 256 char support
- no opt widechar support

xterm now wants xtermcfg.h to build.