Typically only one of the character error conditions is true at a time. And
even if multiple errors were present at the same time we'd only want to
count one error per character.
For each character track whether at least one of the monitored error
conditions is true. Then count the number of characters for which at least
one error condition occurred. And finally add that sum to the total numbers
of errors.
This results in a slightly better utilization.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>