This form delegates the knowledge of the time zone information to an external compiled zoneinfo file (à la BSD).
Caveat: Each time the gettimeofday() function is called, the external zone info is read in again (at least on some SVR4 systems). That results in three wasted system calls with every apache request served.
open("/usr/lib/locale/TZ/MET", O_RDONLY) = 3
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 7944) = 778
close(3) = 0