staging: Sync zsmalloc to latest upstream version
staging: Sync zcache to latest upstream version
zcache-main: enable zcache by default

Signed-off-by: Paul Reioux <reioux@gmail.com>
zcache-main.c: use MACRO define instead of hardcoded default of lzo

Signed-off-by: Paul Reioux <reioux@gmail.com>
zcache-main: switch to lz4 as default

Signed-off-by: Paul Reioux <reioux@gmail.com>
LZ4: compression/decompression signedness mismatch (v2)

LZ4 compression and decompression functions require different
in signedness input/output parameters: unsigned char for
compression and signed char for decompression.

Change decompression API to require "(const) unsigned char *".

v2: minor coding style fix.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	include/linux/lz4.h
	lib/lz4/lz4_decompress.c
Revert "LZ4: compression/decompression signedness mismatch (v2)"

This reverts commit 225b3ad26508fad38da8e4d08389b56e658b9265.