syscall: mksyscall_windows.pl should output unix newline.

R=golang-dev, bradfitz, alex.brainman
CC=golang-dev
https://golang.org/cl/4601058
diff --git a/src/pkg/syscall/mksyscall_windows.pl b/src/pkg/syscall/mksyscall_windows.pl
index fb5a127..83f5f03 100755
--- a/src/pkg/syscall/mksyscall_windows.pl
+++ b/src/pkg/syscall/mksyscall_windows.pl
@@ -27,6 +27,8 @@
 $errors = 0;
 $_32bit = "";
 
+binmode STDOUT;
+
 if($ARGV[0] eq "-b32") {
 	$_32bit = "big-endian";
 	shift;