anonfs: a tmpfs without default_pager

[Sergio López]

Hi,

Some days ago, I came across this tmpfs derived translator I was
working on, which replaces the use of default_pager with a pool of
anonymous memory. I've fixed some pending issues, and updated it to
compile with current Hurd libraries (replacing cthreads with
pthreads). Now it works, but it needs much more testing.

In addition to the backing store replacement, I've used anonfs to test
a trick that avoids dealing with memory objects by breaking libpager's
mechanics, serving read/write requests reading directly from the pool
(as it serves data from memory, it doesn't require caching). It still
implements part of pagers functionality to support mmap'ed files, but
only for reading.

If you want to play with it, you can find it here: https://github.com/slp/anonfs

Sergio.