Wrap bitshifted definitions in parentheses to ensure correct priorities.
Whitespace police.
Also reset "ok" to 0 if the leap second information is processed and the minute length is off by 1 bit.

rval (state) was already set in these cases.
This improves initializing the DST state.
Allow DST changes after the first full minute but not after the second
minute (error cases are already caught by (olderr && ok).
Document why this is needed at all.
Show when the "increase" variable is greater than 1, should not happen.