Impact: add new APIs for binary trace printk infrastructure

vbin_printf(): write args to binary buffer, string is copied
when "%s" is occurred.

bstr_printf(): read from binary buffer for args and format a string

[fweisbec@gmail.com: rebase]
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1236356510-8381-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>