treewide: convert GPLv2+ license info to SPDX tags

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/NativeLibrary.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/overlay/InputOverlay.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.overlay;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/overlay/InputOverlayDrawableButton.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.overlay;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/overlay/InputOverlayDrawableDpad.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2016 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.overlay;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/overlay/InputOverlayDrawableJoystick.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.overlay;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/NVidiaShieldWorkaroundView.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.ui;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/DirectoryInitialization.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2014 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.utils;

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/EGLHelper.java

@@ -1,7 +1,6 @@
 /*
  * Copyright 2013 Dolphin Emulator Project
- * Licensed under GPLv2+
- * Refer to the license.txt file included.
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 package org.dolphinemu.dolphinemu.utils;

Source/Android/jni/AndroidCommon/AndroidCommon.cpp

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "jni/AndroidCommon/AndroidCommon.h"
 

Source/Android/jni/AndroidCommon/AndroidCommon.h

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
 

Source/Android/jni/AndroidCommon/IDCache.cpp

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "jni/AndroidCommon/IDCache.h"
 

Source/Android/jni/AndroidCommon/IDCache.h

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
 

Source/Android/jni/Config/NativeConfig.cpp

@@ -1,6 +1,5 @@
 // Copyright 2020 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <memory>
 #include <string>

Source/Android/jni/Config/PostProcessing.cpp

@@ -1,6 +1,5 @@
 // Copyright 2021 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <string>
 #include <vector>

Source/Android/jni/GameList/GameFile.cpp

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "jni/GameList/GameFile.h"
 

Source/Android/jni/GameList/GameFile.h

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
 

Source/Android/jni/GameList/GameFileCache.cpp

@@ -1,6 +1,5 @@
 // Copyright 2018 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <memory>
 #include <vector>

Source/Android/jni/IniFile.cpp

@@ -1,6 +1,5 @@
 // Copyright 2020 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <jni.h>
 

Source/Android/jni/MainAndroid.cpp

@@ -1,6 +1,5 @@
 // Copyright 2003 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <EGL/egl.h>
 #include <UICommon/GameFile.h>

Source/Android/jni/WiiUtils.cpp

@@ -1,6 +1,5 @@
 // Copyright 2021 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <string>