glibc git commit hooks update.

[DJ Delorie]

For the benefit of those of us who aren't git-savvy, could you please
summarize what a long-term in-branch development process should look
like?  I.e. one that's optimal for our new configuration on sourceware?

I recall going through that with the tcache work, constantly merging
master into the branch, flooding irc, messing up my local repo, and I
recall it was... suboptimal.