gmake output:

functions/datetime.c:67: `timezone' redeclared as different kind of symbol
/usr/include/time.h:116: previous declaration of `timezone'
functions/datetime.c:83: warning: no previous prototype for `_php3_mktime'
gmake: *** [functions/datetime.o] Error 1

from datetime.c:
#if HAVE_TZSET
extern time_t timezone, altzone;
#endif

from /usr/include/time.h:
char *timezone __P((int, int));

I think the extern "timezone" in datetime.c needs
to be turned off in FreeBSD builds. Also the
assignment further in datetime.c should be
bypassed:
gmadjust=timezone/3600;