Implement experimental fusing method.

https://github.com/love2d/love-android/issues/201#issuecomment-772628115

src/modules/filesystem/physfs/Filesystem.cpp

@@ -108,6 +108,10 @@ Filesystem::Filesystem()
 
 Filesystem::~Filesystem()
 {
+#ifdef LOVE_ANDROID
+	love::android::deinitializeVirtualArchive();
+#endif
+
 	if (PHYSFS_isInit())
 		PHYSFS_deinit();
 }
@@ -224,6 +228,31 @@ bool Filesystem::setSource(const char *source)
 	if (!love::android::createStorageDirectories())
 		SDL_Log("Error creating storage directories!");
 
+	new_search_path = "";
+
+	PHYSFS_Io *gameLoveIO;
+	bool hasFusedGame = love::android::checkFusedGame((void **) &gameLoveIO);
+
+	if (hasFusedGame)
+	{
+		if (gameLoveIO)
+		{
+			// Actually we should just be able to mount gameLoveIO, but that's experimental.
+			gameLoveIO->destroy(gameLoveIO);
+			goto oldschool;
+		}
+		else
+		{
+			if (!love::android::initializeVirtualArchive())
+			{
+				SDL_Log("Unable to mount AAsset: %s", PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode()));
+				return false;
+			}
+		}
+	}
+	else
+	{
+	oldschool:
 		new_search_path = love::android::getSelectedGameFile();
 
 		// try mounting first, if that fails, load to memory and mount
@@ -250,6 +279,7 @@ bool Filesystem::setSource(const char *source)
 				return false;
 			}
 		}
+	}
 #else
 	// Add the directory.
 	if (!PHYSFS_mount(new_search_path.c_str(), nullptr, 1))