freebsd stable - May 2010 - libdispatch : queue_kevent.c:204:20: use of undeclared identifier 'EV_RECEIPT'

Hey,

i have followed the instruction emtioed in;

http://wiki.freebsd.org/GCD

but when i compiled libdispatch-r174 i got seven errors like;

libdispatch : queue_kevent.c:204:20: use of undeclared identifier
'EV_RECEIPT'?

is there some bug in source code of libdisptch or freeBSD upgradation to 8.0
stable.

for upgradation i have followed;

http://www.freebsd.org/doc/en/books/handbook/makeworld.html

to upgrade source code.

please tell me how remove this bug.

Thanks,
Faiza