[PREVIEW] Large Rock and Collapsed Forwarding

Hello,

    The attached patch implements Large Rock and Collapsed Forwarding
support. The following Launchpad branch contains detailed commit
messages, most of which would be good for merging back into trunk:

This email summarizes what works and what does not. What works in our
lab tests:

* Large Rock support (caching of arbitrary large files using rock
cache_dirs).

* Collapsed Forwarding support when the response is [eventually] cached
in memory.

What has not been tested and probably needs more work or at least polishing:

* Collapsed Forwarding support when the response is [eventually] cached
on disk.

* 32-bit OS support (there is one 64bit Atomic -- swap_file_sz).

* I need to check that all new declarations have descriptions and resync
with trunk.

I do not expect significant changes going forward, but I am
uncomfortable calling this a "[PATCH]" at this time because of the above
caveats.

The above features were initially tested in non-SMP mode (and worked
OK), but all recent work and tests were focusing on SMP configurations.

HTH,

Alex.