- update to 1.8.1:
* In v1.8, libgit2 introduced the `report_unchanged ` member in
the `git_fetch_options` structure. We mistakenly introduced
this as a bitfield, which is not suitable for our public API.
To correct this mistake, we have _removed_ the
`report_unchanged ` member. To support the report unchanged
tips option, users can set the `update_fetchhead`
member to include the `GIT_REMOTE_UPDATE_REPORT_UNCHANGED`
value.
* The libgit2 projects regrets the API change, but this was
required to support cross-platform compatibility.
* commit: Fix git_commit_create_from_stage without author and
* committer
* process.c: fix environ
* Bounds check for pack index read
* transport: provide a useful error message during cancellation
* transport: support sha256 oids
* Revparse: Correctly accept ref with '@' at the end
* remote: drop bitfields in git_remote_fetch_options
* examples: fix memory leak in for-each-ref.c
* xdiff: use proper free function
* rand: avoid uninitialized loadavg warnings
* cli: include alloca on illumos / solaris / sunos
* Update git_array allocator to obey strict aliasing rules
* tree: avoid mixed signedness comparison by @ethomson in

- require library required by pkg-config file
* fix out-of-bounds reads when processing smart-protocol "ng"
- Changed API:
- Fix license to be GPL-2.0-with-GCC-exception