Adjusts refs::list test (including the comments)
Adjusts objects::tags::list test

This patch changes the tag listing test helper to use a struct as input
parameter, which tells what we exactly expect.

As I don't think, we can rely on the fact that every os and every
filesystem will report the tags in the same order, I made this code
independent of the order that the tags are retrieved.

Since quite a while now, git_branch_foreach has learnt to list branches
without the 'refs/heads/' or 'refs/remotes' prefixes.
This patch teaches git_tag_list to do the same for listing tags.

Make clear that git_odb_hashfile does not use filters

Signed-off-by: Sven Strickroth <email@cs-ware.de>

checkout: add notification callback for skipped files

git_repository_hashfile: Only close file handle if we have a valid one

Otherwise this throws an exception on MFC based systems.

Signed-off-by: Sven Strickroth <email@cs-ware.de>

Checkout, reset and others enhancements

Allocate a buffer large enough to store the path plus the terminator
instead of letting readlink write beyond the end.

odb_pack: make sure to search all backends

last_found is the last packfile a wanted object was found in. Since
last_found is shared among all searching threads, it might changes while
we're searching. As suggested by @arrbee, put a copy on the stack to fix
the race condition.

refs: prevent locked refs from being enumerated

Fix #936

Defining the BOM as a string makes the array include the
NUL-terminator, which means that the memcpy is going to check for that
as well and thus never match for a nonempty file.

Define the array as three chars, which makes the size correct.

I don't think clone.c needs in #include dirent.h and it is not
portable, so let's just get rid of it.

Fix MSVC compilation warnings

pack: iterate objects in offset order

Compute the ordering on demand and persist until the index is freed.

The winhttp branch was based on a version before these existed, so the
build broke on Windows.