Update devel/qgit to latest upstream 2.8

https://github.com/tibirna/qgit/releases/tag/qgit-2.8

Version 2.8 releases fixes for a set of issues that were
reported and/or solved by QGit contributors in the last year.

Most notably, the file browsing was fixed. A set of issues
with compilation on Windows was also addressed. Breakage of
keybindings and menu item accelerators was also sorted out.

The new patch in files/ is there because the release forgot to update
the version number (reported upstream).

Reported by: portsmon