> compiling ../../../ext/socket/socket.c
> ../../../ext/socket/socket.c: In function 'rsock_sock_s_socketpair':
> ../../../ext/socket/socket.c:114:5: warning: implicit declaration of function 'socketpair'

This warning shouldn't be happen. But I'm wondering it because many
people did success mingw32 build. Hmm..

Luis, do you have any opinion? (note: this is head of ruby_1_9_3 branch).