poke: update to 3.1.

Version 3.1 (17 April 2023)
* Bug fixes

   - Fix recognition of token 0[bB] in the lexer.

   - Do not validate and check _print* functions within struct types
     as if they were methods.  As functions, they can have any
     signature as they are no special in any way.

   - Do not emit an empty table for computed fiels in the output of
     .info type if the type has no computed fields.

   - Use tar-ustar in AM_INIT_AUTOMAKE.  The usage older algorithms in
     tar was causing problems when creating poke tarballs with long
     path names.

   - std.pk now provides utility functions to parse and compare poke
     versions.  This is for example to be used by poke pickles in
     order to require a particular minimum version of the program.

   - poked now recognizes the short option -S.

   - poked now creates its socket with umask 0077, and it uses a more
     suitable default socket path that includes the PID of the process
     running the daemon.

   - The Poke compiler now emits proper parse errors when problems are
     found in asm templates.

   - poke will no longer abort execution in case it finds a fatal
     error in the lexer, such as memory exhaustion.

   - Casts from arrays to arrays now use the right bounder.

   - Constant folding of offset multiplication by an offset with zero
     unit is now fixed.


(fcambus)