v5.4.2
Update m4/.gitignore.
Fix bugs and otherwise improve ax_check_capsicum.m4.
Build: Update m4/ax_pthread.m4 from Autoconf Archive.
Fix the Autoconf test for getopt_long replacement. It was broken by e114502.
Major update to the xzgrep and other scripts based on the latest versions found from gzip CVS repository.
Various changes.
tuklib_cpucores: Use HW_NCPUONLINE on OpenBSD.
Build: Update comments about unaligned access to mention 64-bit.
xz: Multiple fixes.
tuklib: Omit an unneeded <sys/types.h> from a tests.
Build: Fix config.h comments.
Build: Add visibility.m4 from gnulib.