Make crossystem.h more polite and more useful.

This adds a VB_MAX_STRING_PROPERTY for callers that don't
want to guess at how big to make their buffers.

Additionally, it changes the size parameter to VbGetPropertyString()
from int to size_t.

TEST=compile the code

Change-Id: I22809d48e13b535593cb22a56444e2dcb27791a5
Reviewed-by: Randall Spangler <>
Tested-by: Richard Barnette <>
Reviewed-by: Bill Richardson <>
Commit-Queue: Richard Barnette <>
6 files changed