master
Remove m4/c-bool.m4, update other files as needed.
Merge branch 'gawk-5.4-stable'
Update gettext version in the doc.
Update lots of files because of change of FSF address.
Restore iconv.m4.
Squashed commit of the following:
Further support updates from GNULIB.
Fix a regex bug in charset.
Update charset and minrx.
Update support files.
Update some of the support files.
Sync support with GNULIB.
Small fix in getopt.c.
Add some prototypes in missing_d files for musl libc.
Add small regex fix. Add support directory.
Merge branch 'master' into feature/nuke-m4-files
Update minrx.c from upstream: memory management improvements.
Simplify change to pma.c.
Add extern "C" stuff to pma.h.
Update random.c to use prototypes.
Small fix in regcomp.c.
Update copyright years, some other small cleanups.