SDLActivity.java: Compatibility fix for debugSource

I did these fixes a while ago while debuggin my application, however, forgot to send them back.

android-project/app/src/main/java/org/libsdl/app/SDLActivity.java

@@ -84,7 +84,7 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
 
 
         int s2 = s_copy & ~InputDevice.SOURCE_ANY; // keep class bits
-        s2 &= ~(  InputDevice.SOURCE_CLASS_BUTTON 
+        s2 &= ~(  InputDevice.SOURCE_CLASS_BUTTON
                 | InputDevice.SOURCE_CLASS_JOYSTICK
                 | InputDevice.SOURCE_CLASS_POINTER
                 | InputDevice.SOURCE_CLASS_POSITION
@@ -94,9 +94,11 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
 
         s2 = s_copy & InputDevice.SOURCE_ANY; // keep source only, no class;
 
-        tst = InputDevice.SOURCE_BLUETOOTH_STYLUS;
-        if ((s & tst) == tst) src += " BLUETOOTH_STYLUS";
-        s2 &= ~tst;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            tst = InputDevice.SOURCE_BLUETOOTH_STYLUS;
+            if ((s & tst) == tst) src += " BLUETOOTH_STYLUS";
+            s2 &= ~tst;
+        }
 
         tst = InputDevice.SOURCE_DPAD;
         if ((s & tst) == tst) src += " DPAD";
@@ -106,9 +108,11 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
         if ((s & tst) == tst) src += " GAMEPAD";
         s2 &= ~tst;
 
-        tst = InputDevice.SOURCE_HDMI;
-        if ((s & tst) == tst) src += " HDMI";
-        s2 &= ~tst;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            tst = InputDevice.SOURCE_HDMI;
+            if ((s & tst) == tst) src += " HDMI";
+            s2 &= ~tst;
+        }
 
         tst = InputDevice.SOURCE_JOYSTICK;
         if ((s & tst) == tst) src += " JOYSTICK";
@@ -143,9 +147,11 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
         if ((s & tst) == tst) src += " TOUCHSCREEN";
         s2 &= ~tst;
 
-        tst = InputDevice.SOURCE_TOUCH_NAVIGATION;
-        if ((s & tst) == tst) src += " TOUCH_NAVIGATION";
-        s2 &= ~tst;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
+            tst = InputDevice.SOURCE_TOUCH_NAVIGATION;
+            if ((s & tst) == tst) src += " TOUCH_NAVIGATION";
+            s2 &= ~tst;
+        }
 
         tst = InputDevice.SOURCE_TRACKBALL;
         if ((s & tst) == tst) src += " TRACKBALL";