syscall: fix Windows Signalled
syscall: fix Windows Signalled

Thanks to fhs.

R=golang-dev, r2
CC=ality, fhs, golang-dev
http://codereview.appspot.com/4375044

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