lib/, src/: Turn error counters into flags

lib/, src/: Turn error counters into flags

If we are not interested in the amount of errors but only if errors
exist, use a flag instead of a counter. This eliminates the chance of
signed integer overflows and better reflects the meaning of variable.

Keeping variable name and basically copied from src/faillog.c.

Reviewed-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>