Move workarounds to a separate class

Extract workarounds (currently only one) to a separate class to avoid
polluting the main code.

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

@@ -8,7 +8,6 @@
 import android.media.MediaFormat;
 import android.os.Build;
 import android.os.IBinder;
-import android.os.Looper;
 import android.view.Surface;
 
 import java.io.FileDescriptor;
@@ -53,15 +52,7 @@ public boolean consumeRotationChange() {
     }
 
     public void streamScreen(Device device, FileDescriptor fd) throws IOException {
-        // Some devices internally create a Handler when creating an input Surface, causing an exception:
-        //   "Can't create handler inside thread that has not called Looper.prepare()"
-        // <https://github.com/Genymobile/scrcpy/issues/240>
-        //
-        // Use Looper.prepareMainLooper() instead of Looper.prepare() to avoid a NullPointerException:
-        //   "Attempt to read from field 'android.os.MessageQueue android.os.Looper.mQueue'
-        //    on a null object reference"
-        // <https://github.com/Genymobile/scrcpy/issues/921>
-        Looper.prepareMainLooper();
+        Workarounds.prepareMainLooper();
 
         MediaFormat format = createFormat(bitRate, maxFps, iFrameInterval);
         device.setRotationListener(this);

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

@@ -0,0 +1,21 @@
+package com.genymobile.scrcpy;
+
+import android.os.Looper;
+
+public final class Workarounds {
+    private Workarounds() {
+        // not instantiable
+    }
+
+    public static void prepareMainLooper() {
+        // Some devices internally create a Handler when creating an input Surface, causing an exception:
+        //   "Can't create handler inside thread that has not called Looper.prepare()"
+        // <https://github.com/Genymobile/scrcpy/issues/240>
+        //
+        // Use Looper.prepareMainLooper() instead of Looper.prepare() to avoid a NullPointerException:
+        //   "Attempt to read from field 'android.os.MessageQueue android.os.Looper.mQueue'
+        //    on a null object reference"
+        // <https://github.com/Genymobile/scrcpy/issues/921>
+        Looper.prepareMainLooper();
+    }
+}