These operations may fail with some crypto wrappers, so allow the
functions to report their results to the caller.
Signed-off-by: Jouni Malinen <j@w1.fi>
Some crypto libraries can return in these functions (e.g., if a specific
hash function is disabled), so we better provide the caller a chance to
check whether the call failed. The return values are not yet used
anywhere, but they will be needed for future changes.