fixed build error of windows

backend/services/sys_exec/linux_mac.go

@@ -0,0 +1,30 @@
+// +build !windows
+
+package sys_exec
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+func BuildCmd(cmdStr string) *exec.Cmd {
+	return exec.Command("sh", "-c", cmdStr)
+}
+
+func Setpgid(cmd *exec.Cmd) {
+	if cmd == nil {
+		return
+	}
+	if cmd.SysProcAttr == nil {
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	} else {
+		cmd.SysProcAttr.Setpgid = true
+	}
+}
+
+func KillProcess(cmd *exec.Cmd) error {
+	if cmd == nil {
+		return nil
+	}
+	return syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+}