Add Multi Window support for Samsung devices

A single meta-data entry is enough to make Termux "Multi Window" aware on supported Samsung devices.
Tested and confirmed working on Samsung Note Pro 12.2 running Android 5.1.1.

This addition should not interfer with Android 6+'s split screen feature.
Tested and confirmed split screen functions as normal on a Nexus 6 running Android 7.0.

This addition should go unnoticed on non-Smasung Android 5 devices.
Tested and confirmed no functionality visible on Nexus 5 running Android 5.1.

app/src/main/AndroidManifest.xml

@@ -99,6 +99,7 @@
                   android:grantUriPermissions="true"
                   android:name="com.termux.app.TermuxOpenReceiver$ContentProvider" />
 
+        <meta-data android:name="com.sec.android.support.multiwindow" android:value="true" />
     </application>
 
 </manifest>