rxvt-unicode: upgrade 9.30 -> 9.31

Changelog:
===========
- implement a fix for CVE-2022-4170 (reported and analyzed by David Leadbeater).
  While present in version 9.30, it should not be exploitable. It is exploitable
  in versions 9.25 and 9.26, at least, and allows anybody controlling output to
  the terminal to execute arbitrary code in the urxvt process.
- the background extension no longer requires off focus fading support
  to be compiled in.
- the confirm-paste extension now offers a choice betwene pasting the original
  or a sanitized version, and also frees up memory used to store the paste text
  immediately.
- fix compiling without frills.
- fix rewrapMode: never.
- fix regression that caused urxvt to no longer emit responses
  to OSC color queries other than OSC 4 ones.
- fix regression that caused urxvt to no longer process OSC 705.
- restore CENTURY to be 1900 to "improve" year parsing in urclock (or at
  least go back to the old interpretation) (based on an analysis
  by Tommy Pettersson).
- exec_async (used e.g. by the matcher extension to spawn processes) now
  sets the URXVT_EXT_WINDOWID variable to the window id of the terminal.
- implement -fps option/refreshRate resource to change the default 60 Hz
  maximum refresh limiter. I always wanted an fps option, but had to
  wait for a user requesting it.
- new clickthrough extension.
- perl now also requires Xext.
- X region and shape extension functionality has been exposed to perl
  extensions.
- RENDER extension no longer depends on ENABLE_XIM_ONTHESPOT.

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>