[openib-general] cannot clone librdmacm

[Roland Dreier]

 > Right, and everyone can enable this, if _he_ wants.

I think the point is that in the OFA environment, there's no obvious
reason to disable the hook, since without the hook http:// transport
is broken.

So it makes sense to help people who aren't necessarily git experts,
and pick a default that makes things work smoothly.  Experts can
disable the hook if there's some reason to do so (although to be
honest I don't see any reason).

 - R.