S9 LIB  (time->unix-time time-list)  ==>  integer | #f

        (load-from-library "time-to-unix-time.scm")

TIME->UNIX-TIME converts TIME-LIST (see UNIX-TIME->TIME) to the
number of seconds since the Unix epoch. It returns #F if TIME-LIST
is not a proper time list.

(time->unix-time '(6 2010 4 25 7 1 19))  ==>  1272178879
