portable: fix compilation on OpenBSD Make -portable work on OpenBSD; explicitly use -ltls, and dont't use PKG_CONFIG to check for a library which won't exist on OpenBSD.

portable: enable SHA256 This allows the use of native SHA256 functions. From naddy@

portable: disable SHA384/SHA512 This isn't used in got, so may as well disable from compat. From naddy@

portable: compile gotd unconditionally For some time now, gotd was only ever available if one used the --enable-gotd flag to configure. This was fine back when gotd was still under development -- but it's now very usable, and deserves to be enabled by default.

portable: update help syntax Fix syntax for --enable-{gotd,cvg}

portable: enable got-fetch-http

portable: gotd: enable got-notify-http

portable: enable got-notify-email Now that gotd has the start of helpers, got-notify-email is the first. This is still behind the --enable-gotd flag.

portable: update dist configuration When running 'make dist', ensure we automatically pass through the relevant configure options so that the relevant files are included.

portable: add --enable-cvg flag Just while cvg is being developed, mask the building of this via a flag to ./configure -- this is not intended to be used by any packagers, but rather, provide a means for developers for testing. This flag will go away once cvg is considered releasable.

portable: configure: echo gotd/gitwrapper paths When --enable-gotd is present, and gotd empty path or gitwrapper's git libexec path is set, print those out with the other information at the end of the configure script. "N/A" is set where no value is present. Helpful for debugging.

portable: make gitwrapper --enable-gotd aware There's no point installing gitwrapper outside of enabling gotd, as this is only used by gotd.

portable: configure gitwrapper/gotd paths Rather than hard-code assumptions into gitwrapper and gotd binaries, allow for some values to be overriden at compile time. This should help portability.

portable: gotd/gitwrapper: update for libs Bring gotd and gitwrapper closer to how libraries are detected.

portable: enable gotctl (via --enable-gotd) This builds gotctl, for the moment via --enable-gotd

portable: build gotsh when --enable-gotd passed When building gotd, also build gotsh.

portable: enable compiling gotd This enables gotd -- for now, this is opt-in at compile-time, via: ./configure --enable-gotd

portable: enable cvg

portable: linux: add libmd On some systems libmd isn't explicitly implied, so detect this via pkg-config at configure time. Problem reported by @stsp

portable: fix getopt check Rather than always asserting our version of getopt(2), only do so if it lacks certain features. Some of the changes have come from openssh-portable.

portable: OpenBSD compilation fixes

portable: curses: improve detection When checking for ncurses, don't clobber previous checks for libpanel.

portable: improve b64_ntop detection When looking for base64 functions, check -lresolv and/or -lnetwork, and only build those in compat if required. Some of the detection code was modified from tmux's script.

portable: add missing header checks Some code in compat/ has #defines which were not being checked for in, which could have lead to compilation failures were those files to be included on systems which needed them. In doing so, we can now remove libmd and libcrypto as these are no longer needed.

portable: configure: use SHA_2{,56}_H Don't use a custom variable when the header checks for these are already available. From Christian "naddy" Weisgerber.