Since C++17 is now the default mosh version, remove the shared_ptr
shim in favor of std::shared_ptr.

Previously, mosh used extensive -I flags and all of the mosh-local
makes it really hard to tell what the proper dependency graph is, so
instead remove the -I arguments in favvor of $(top_srcdir) and qualify
the paths wherever they are used.

-I$(top_srcdir) is not usable on macOS due to a conflicting C++ header
 `version`.

ubuntu-18.04 is no longer available on Github Actions; replace it with
ubuntu-22.04.

Protobuf versions since 3.6.0 have long had a C++11 dependency; even
more recent versions have picked up an Abseil dependency bumping that
to C++14. Since it is now 2023, defaulting to C++17 is reasonable, so
remove the conditional C++ standards version check that mosh
previously had and replace it with an unconditional C++17 check.

This means that all future commits can use C++17 features. According
to https://en.cppreference.com/w/cpp/compiler_support/17 this means
that minimum effective compiler versions for mosh become:

gcc 7 (May 2017)
clang 5 (September 2017)

This, in turn, implies that future versions of mosh will no longer be
available for RHEL/CentOS 7 (June 2014).

Closes: #1267

* Add developer instructions to readme

* Split dependencies by platform

* Remove unneeded packages

Signed-off-by: David Korczynski <david@adalogics.com>

experimental is spelled “experimental”, not “unstable”. Oops. Fix
3006ce6d’s debian/changelog.

Per release-team’s recent request that maintainers support the nocheck
profile <E1oit90-0073rh-LX@respighi.debian.org>, annotate build
dependencies that are test-only with <!nocheck>.

tmux 3.3a has a behavior change, since reverted, that is incompatible
with this test. Unfortunately, tmux 3.3a has already made it into some
distributions, so the test has to be disabled when tmux 3.3a is encountered.

This helps to avoid problems when the 1.4.0 release is made and
distributions with version sort order think the rc sorts after
the non-suffixed version

`git fetch --tags --unshallow`, run as part of the CI for `git
describe` to do the right thing, ran into the error:

```
 ! [rejected]        mosh-1.4.0-rc0   -> mosh-1.4.0-rc0  (would clobber existing tag)
```

This is because mosh uses annotated tags, whereas the initial fetch
command run by actions/checkout@v2 ends up creating an *unannotated*
tag of the same name.

This means that any time the release CI runs, it would fail.

The resolution is straightforward: --force so that the line becomes

```
 t [tag update]      mosh-1.4.0-rc0 -> mosh-1.4.0-rc0
```

and the annotation is brought in.

The previous CI attemtped to use Homebrew for builds, but
unfortunately Homebrew has dropped support for universal packages aka
multiarch (fat) binaries. This means that in order to build an arm64 +
x86_64 package, macports has to be used instead of homebrew.

Unlike Homebrew, MacPorts is not installed by default on the GitHub
Actions runners, so we need to install it ourselves. This means
managing our own instance of the cache, which itself produces
challenges as the `gtar` binary run by the action doesn't have enough
permissions to restore the MacPorts checkout. So we have to shim gtar
with a sudo wrapper.

With this commit, we produce a Mosh package that works on macOS 11.0
and newer, on both arm64 and x86_64 architectures. The protobuf
library is statically linked, but all other libraries are provided by
the system.

Work around protocolbuffers/protobuf#10357 by disabling
-Wunused-parameter.

This change ports the Travis CI release workflow for macOS to Github
Actions. Note that while this is functionally identical to the
previous Travis CI flow, no work has been done to update the macOS
build scripts to build for arm64.

This Github Actions workflow uses a Linux-based running to create the
release tarball for mosh. This is necessary since mosh does not check
in the autoconf/automake generated files, so the default release
action source download is missing files that are needed for
distributions that use the upstream-provided ./configure script.

Replace calls to AES_* APIs, which were deprecated in OpenSSL 3, with
calls to EVP_* APIs.

Closes: https://github.com/mobile-shell/mosh/issues/1174

Previously, ocb_internal.cc supported different key sizes, by way of
the deprecated aes_* function family. However, in practice, mosh
always uses AES-128. In Nettle, the explicit key-size APIs are not
deprecated, so switch to AES-128 directly.

Fixes: 1202

The OpenSSL EVP API requires that keys be heap-allocated, so switch
_ae_ctx to use pointers to keys and opaque allocation functions.

Bug: https://github.com/mobile-shell/mosh/issues/1174

Explicitly define the primitive AES API used by the internal OCB
implementation, and move it into its own namespace (ocb_aes). This will
ease future implementation changes.

Also make some style fixes to affected lines: Replace C-style casts
with C++-style casts, add some missing spaces in argument lists, and
remove some `inline` that the compiler will ignore.

Bug: https://github.com/mobile-shell/mosh/issues/1174

This macro was used in the reference and AES-NI AES implementations,
both of which were deleted in a563093f.