syscall: handle EOF on pipe - special case on Windows

R=rsc
CC=golang-dev
https://golang.org/cl/962046

src/pkg/syscall/syscall_windows.go

@@ -184,6 +184,10 @@ func Open(path string, mode int, perm int) (fd int, errno int) {
 func Read(fd int, p []byte) (n int, errno int) {
 	var done uint32
 	if ok, e := ReadFile(int32(fd), p, &done, nil); !ok {
+		if e == ERROR_BROKEN_PIPE {
+			// BUG(brainman): work around ERROR_BROKEN_PIPE is returned on reading EOF from stdin
+			return 0, 0
+		}
 		return 0, e
 	}
 	return int(done), 0

src/pkg/syscall/zerrors_windows_386.go

@@ -8,6 +8,7 @@ package syscall
 const (
 	ERROR_FILE_NOT_FOUND      = 2
 	ERROR_NO_MORE_FILES       = 18
+	ERROR_BROKEN_PIPE         = 109
 	ERROR_INSUFFICIENT_BUFFER = 122
 	ERROR_MOD_NOT_FOUND       = 126
 	ERROR_PROC_NOT_FOUND      = 127