Backported ZCache mechanism from Linux Kernel 3.9.11

Conflicts:
	drivers/staging/zcache/Kconfig
	drivers/staging/zcache/Makefile
	drivers/staging/zcache/tmem.c
	drivers/staging/zcache/tmem.h
	drivers/staging/zcache/zcache-main.c
Remove unused files

Conflicts:
	drivers/staging/zcache/zcache.c
Adapt ZCache from kernel 3.9 to kernel 3.0
Backport Frontswap frontend mechanism from kernel 3.9

Conflicts:
	mm/frontswap.c
Update zcache to Linux kernel 3.11
Backport zbud from kernel 3.11

Conflicts:
	mm/Kconfig
	mm/Makefile
fix le build