Merge pull request libgit2#2815 from ethomson/example

clone example: don't divide by zero

Reformat the changelog

This should provide a easier way to see what kinds of changes we have,
and a single place to look at the breaking changes.

Fix assert when receiving uncommon sideband packet

Merge pull request libgit2#2801 from ethomson/changelog

CHANGELOG: add missing 0.22 changes

index tests: test capitalization before mkdir

Bump version to 0.21.2

array: mark the array to grow as volatile

This works around strict aliasing rules letting some versions of
GCC (particularly on RHEL 6) thinking that they can skip updating the
size of the array when calculating the next element's offset.

libgit2 v0.21.0

Merge pull request libgit2#2425 from libgit2/cmn/clone-auth-change

Don't use read-write accounts for the tests

Merge pull request libgit2#2407 from libgit2/cmn/remote-rename-more

More remote rename fixes