Compatibility/Portability cleanup

* Removes mingw-compat.h
* Cleans up separation of compiler/platform idiosyncrasies
* Unifies mingw/msvc stat structures and functions
* (Tries to) hide more compiler specific implementation details (even in our internal API)

Solaris doesn't necessarily have stdint.h, use inttypes.h

Work around strict aliasing in array growth

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.

Preallocating two commits doesn't make much sense as leaving allocation
to the first array usage will allocate a sensible size with room for
growth.

This preallocation has also been hiding issues with strict aliasing in
the tests, as we have fairly simple histories and never trigger the
growth.

Don't allow conflicts by default

Fix git status list new unreadable folder

Rename git_cherry_pick to git_cherrypick

Export git_buf_text_is_binary and git_buf_text_contains_nul.

When adding new config section, handle config file not ending with LF

Handle local file:/// paths on Windows

So that users don’t need to implement binary detection themselves.

Update perl bindings link

Switch description and message reporting in `clar__assert_equal_file`

Windows can't handle a path like `/c:/foo`; when turning file:///
URIs into local paths, we must strip the leading slash.

Windows compatibility fixes 

ssh: provide a factory function for setting ssh paths