libostree: Allow compression level to be set for archive-z2 stream
Add a ostree_raw_file_to_archive_z2_stream_with_options() variant of
ostree_raw_file_to_archive_z2_stream(), to allow a compression-level
option to be passed in and passed through to zlib.
This is useful when building archive-z2 files on the fly for
transmission over a non-bandwidth-limited channel, such as a local
network. In this case, CPU time is more valuable than bandwidth, so we
want a low compression level.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Closes: #721
Approved by: cgwalters