ci: allow workflows to read and write packages

Git blame buffer gives the wrong result in many cases where there are…

cmake: rename FindIconv to avoid collision with cmake

Our CI workflows consume and will automatically generate their build
containers. Ensure that they can do so.

cmake now includes `FindIconv`. Rename ours to avoid any confusion.

actions: set permissions

Several compatibility fixes

We now allow leading and trailing dots in username and email addresses.
Test that we do so.

clone: don't mix up "http://url" with "http:/url" when figuring out if we should do a local clone

process: test /usr/bin/false on BSDs

Support setting oid type for in-memory repositories

Pass a pointer to the quote counts so that we can increment it.

Ensure that we declare variables at the top of the block for broad
compatibility with old compilers.

push: set generic error in push_negotiation cb

release: add a compatibility label

Add a compatibility label to the release.yml to describe things that are for improved cross-platform compatibility.

When a user returns `-1` in a `push_negotiation` callback, we set the
error to whatever's hanging out in the buffer, probably something about
a missing configuration entry.

Clear the error buffer before invoking the callback, so that if a user
does not set an error message in their callback that we can detect. If
there is no error but `-1` is returned, set a generic error message.

fetch: enable deepening/shortening shallow clones

util: suppress some uninitialized variable warnings

Avoid macro redefinition of ENABLE_INTSAFE_SIGNED_FUNCTIONS

git2: Fix crash when called w/o parameters

Signed-off-by: Sven Strickroth <email@cs-ware.de>

Our process tests were previously testing that false is
`/bin/false` everywhere except macOS, where it exists as
`/usr/bin/false`. . Extend this to all BSDs.

Signed-off-by: Sven Strickroth <email@cs-ware.de>

ci: overwrite nonsense in /usr/local during macOS setup

GitHub Actions has borked their homebrew setup by first `brew
installing` things into `/usr/local` _and then_ putting their
own things in their place (eg `python`).

This breaks Homebrew, since it thinks it has `python` installed, but
it's actually something else.

Try to avoid using things that are in this bad state.

https://github.com/orgs/community/discussions/78266

A shallow repository can currently only be completely unshallowed, which
is caused by mark_local() only marking locally-existing objects as
wanted if the fetch depth is set to INT_MAX (GIT_FETCH_DEPTH_UNSHALLOW).
This prevents deepening the history of a shallow clone to an arbitrary
number of commits, which may be preferable over full unshallowing for
large repositories.

Enable deepening and shortening shallow clones by marking
locally-existing objects as wanted whenever the fetch depth is set to
any non-default value (either GIT_FETCH_DEPTH_UNSHALLOW or an arbitrary
positive integer).