New git email hook

[Zack R. <za...@tu...>]

Hey,

I've replaced the script we've been using for the Mesa Git repo with a modified 
version of the script used by the Wine guys.

Basically the differences are as following:

1) If the push has less than 20 commits then they will be sent as individual 
emails

2) Each one of the individual emails will have a link to the cgit commit plus 
the diff. The diff will only be included for diff 50k or smaller, larger one will 
produce emails with only the commit message.

3) The subject line includes the first line of the commit message, which is a 
standard in Git but we haven't been too good at following it. So if commiting 
try to have : a) first line of the commit message description of what it does, 
b) a newline and description of what it does

4) If the number of commits is larger than 20 (e.g. merging a branches) then 
the email should look more less like the ones we're currently receiving 
(meaning: one email with just commit messages for all commits).

I just pused two commits so you can see how the individual emails will look 
based on those.
Hope this won't cause too much trouble but I think long term this will be a 
lot more useful.

z