Untangle git_futils_mkdir from git_futils_mkdir_ext - the latter
assumes that we own everything beneath the base, as if it were
being called with a base of the repository or working directory,
and is tailored towards checkout and ensuring that there is no
bogosity beneath the base that must be cleaned up.
This is (at best) slow and (at worst) unsafe in the larger context
of a filesystem where we do not own things and cannot do things like
unlink symlinks that are in our way.
git_index_add_frombuffer enables now to store a memory buffer in the odb
and to store an entry in the index directly if the index is attached to a
repository.
Introduce `git_indexwriter`, to allow us to lock the index while
performing additional operations, then complete the write (or abort,
unlocking the index).
Path validation may be influenced by `core.protectHFS` and
`core.protectNTFS` configuration settings, thus treebuilders
can take a repository to influence their configuration.
This fixes a typo I made for setting the sorted flag on the index
after a reload. That typo didn't actually cause any test failures
so I'm also adding a test that explicitly checks that the index is
correctly sorted after a reload when ignoring case and when not.
This updates the git_pqueue to simply be a set of specialized
init/insert/pop functions on a git_vector.
To preserve the pqueue feature of having a fixed size heap, I
converted the "sorted" field in git_vectors to a more general
"flags" field so that pqueue could mix in it's own flag. This
had a bunch of ramifications because a number of places were
directly looking at the vector "sorted" field - I added a couple
new git_vector helpers (is_sorted, set_sorted) so the specific
representation of this information could be abstracted.
