may have ways of getting the request time without the extra syscall, but
for now let's just make sure we don't crash and people will eventually
fill these in where applicable.
"Furthermore, since there is not a one-to-one correspondence between
threads and connections (N connections mapped onto M threads,
M <= N), connection-specific data must be accessed through the handles
provided by the Milter library."
which in other words means php_request_startup() and the corresponding
php_request_shutdown() will never be called for the same thread
reopen file per request, so milter doesn't hang. PHPA or APC can be used to speed the milter up
added a milter_init callback to init the milter before it is registered
added protos to make sniper happy