Start cleanup process with setsid()

Reimplement c59a3c3169 using Os.setsid().

Refs #5613 comment <https://github.com/Genymobile/scrcpy/pull/5613#issuecomment-2527045669>

Suggested-by: Simon Chan <1330321+yume-chan@users.noreply.github.com>

server/src/main/java/com/genymobile/scrcpy/CleanUp.java

@@ -6,6 +6,8 @@ import com.genymobile.scrcpy.util.Settings;
 import com.genymobile.scrcpy.util.SettingsException;
 
 import android.os.BatteryManager;
+import android.system.ErrnoException;
+import android.system.Os;
 
 import java.io.File;
 import java.io.IOException;
@@ -163,6 +165,12 @@ public final class CleanUp {
     }
 
     public static void main(String... args) {
+        try {
+            // Start a new session to avoid being terminated along with the server process on some devices
+            Os.setsid();
+        } catch (ErrnoException e) {
+            Ln.e("setsid() failed", e);
+        }
         unlinkSelf();
 
         int displayId = Integer.parseInt(args[0]);