(FACT-128) Remove use of non-standard 'daylight' variable

The daylight variable is used, but it seems to be non-standard. At least
it doesn't match what's described here:

http://pubs.opengroup.org/onlinepubs/7908799/xsh/time.h.html

which states "The value of tm_isdst is positive if Daylight Saving Time
is in effect, 0 if Daylight Saving Time is not in effect, and negative
if the information is not available."
And hmm, according to http://www.freebsd.org/cgi/man.cgi?query=gettimeofday&sektion=2, FreeBSD doesn't support retrieving timezone via `gettimeofday` either.