console/vsprintf: Implement snprintf

snprintf is a safe variant of sprintf. To avoid buffer overflows
we shouldn't use sprintf at all. But for now let's start by
implementing snprintf in first place.

Change-Id: Ic17d94b8cd91b72f66b84b0589a06b8abef5e5c9
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/4278
Tested-by: build bot (Jenkins)
Reviewed-by: Peter Stuge <peter@stuge.se>
2 files changed