Merge branch 'bs/config-mak-freebsd'

Drop FreeBSD 4 support and assume we are at least at FreeBSD 6 with
memmem() supported.

* bs/config-mak-freebsd:
  build: retire NO_UINTMAX_T
  config.mak.uname: set NO_MEMMEM only for functional version

diff --cc Makefile
Simple merge

diff --cc config.mak.uname
Simple merge

diff --cc configure.ac
Simple merge

diff --cc meson.build
Simple merge