As rpm-ostree evolves, it keeps driving API additions to libostree.
This creates a relatively tight coupling.
However, if delivering via e.g. RPM, unless one manually remembers to
increment the `Requires:` in the spec file, it's possible for the two
to become desynchronized.
RPM handles versioned symbols and will ensure a dependency if the
application starts using a newer version.
To implement this, switch to `-fvisibility=hidden`, along with an
annotation in the header, and finally add a `.sym` file.
This matches what other projects like systemd and libvirt do.
Although rather than attempting to retroactively version symbols, glom
them all onto the current one.
Don't expose GChecksum in APIs. Add a new stream class which allows
us to pass an input stream somewhere, but gather a checksum as it's
read.
Move some bits of the internals towards binary csums.
Colin Walters
Giuseppe Scrivano