Path validation may be influenced by `core.protectHFS` and
`core.protectNTFS` configuration settings, thus treebuilders
can take a repository to influence their configuration.
We cannot know from looking at .gitmodules whether a directory is a
submodule or not. We need the index or tree we are comparing against to
tell us. Otherwise we have to assume the entry in .gitmodules is stale
or otherwise invalid.
Thus we pass the index of the repository into the workdir iterator, even
if we do not want to compare against it. This follows what git does,
which even for `git diff <tree>`, it will consider staged submodules as
such.
* Make GIT_INLINE an internal definition so it cannot be used in
public headers
* Fix language in CONTRIBUTING
* Make index caps API use signed instead of unsigned values
