snprintf: lockless operation

Instead of having global variables put them on the stack.

Change-Id: I462e3b245612ff2dfb077da1cbcc5ac88f8b8e48
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/4288
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
1 file changed