x11/xterm: update to 377

Patch #377 - 2022/11/25

- add control sequences for reporting the current state of the modified keys
  options (XTQMODKEYS) and allowed/disallowed operations (XTQALLOWED),
  (prompted by discussion with Bram Moolenaar).
- amend modifyOtherKeys case 2 to distinguish the escape character with
  modifiers, e.g., shift-escape, from a plain escape character (suggested by
  Bram Moolenaar).
- improve parsing and error-recovery in the case where a list of X11 bitmap
  fonts is given in the -fn and related options.
- change default for xftTrackMemUsage to false, because libXft has does not
  handle certain fonts.

Patch #376 - 2022/11/16

- modify configure script to always check for gcc attributes,
- update install-sh.
- fix parsing of result -u in vttests/halves.pl.
- add a note in ctlseqs.ms about compatibility of TBC.
- fix a copy/paste error in manual (patch by Grady Martin).
- add null-pointer checks in x_strcasecmp and x_strncasecmp, to help with
  error-recovery for a missing font (Debian #1022942).

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