syscall: fix socketpair in syscall_bsd
syscall: fix socketpair in syscall_bsd

THIS WILL BREAK THE BUILD.

The z files have socketpair code in them that was
written by hand; breaking the build with this is the first
step in getting rid of that hand-written code.

R=adg
TBR=adg
CC=golang-dev
http://codereview.appspot.com/2197050

gnanderson/go,tv42/old-go,ssrl/go,dsriram/golang,dsriram/golang,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,pombredanne/go-deleteme,ssrl/go,h8liu/golang,gnanderson/go,ssrl/go,dsriram/golang,gnanderson/go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,ssrl/go,h8liu/golang,pombredanne/go-deleteme,h8liu/golang,tv42/old-go,ssrl/go,h8liu/golang,tv42/old-go,tv42/old-go,dsriram/golang,gnanderson/go,apparentlymart/golang,tv42/old-go,ssrl/go,apparentlymart/golang,h8liu/golang,tv42/old-go,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,apparentlymart/golang,h8liu/golang,h8liu/golang,ssrl/go,apparentlymart/golang,dsriram/golang,gnanderson/go