Compcache: in-memory compressed swapping

> - use mtdram driver to make a MTD device out of ram

mtdram driver simply simulates MTD device in ram - no compression and no memory management (it simply preallocates all the memory). Also, there are unnecessary overheads involved -- simulate erasing eraseblock and such.

> - use jffs2 with compression enabled on the new mtd device
> - put a swapfile on that filesystem and swap to it

Base for this indirection hierarchy is the in-ram mtd device which has problems mentioned above. Also, as amikims pointed out, additional levels of indirection means more overhead.