Properly pause all audio processing in Android when minimized.

This uses ALC_SOFT_pause_device extension which is available since
OpenAL-soft 1.16. We guarantee almost 100% availability of this extension
since we've been using OpenAL-soft in Android since beginning.

Fixes #1828

src/modules/event/sdl/Event.cpp

@@ -627,20 +627,9 @@ Message *Event::convertWindowEvent(const SDL_Event &e)
 		if (auto audio = Module::getInstance<audio::Audio>(Module::M_AUDIO))
 		{
 			if (e.window.event == SDL_WINDOWEVENT_MINIMIZED)
-			{
-				for (auto &src : pausedSources)
-					src->release();
-				pausedSources = audio->pause();
-				for (auto &src : pausedSources)
-					src->retain();
-			}
+				audio->pauseContext();
 			else if (e.window.event == SDL_WINDOWEVENT_RESTORED)
-			{
-				audio->play(pausedSources);
-				for (auto &src : pausedSources)
-					src->release();
-				pausedSources.resize(0);
-			}
+				audio->resumeContext();
 		}
 #endif
 		break;

src/modules/event/sdl/Event.h

@@ -78,10 +78,6 @@ private:
 	static std::map<SDL_Keycode, love::keyboard::Keyboard::Key> createKeyMap();
 	static std::map<SDL_Keycode, love::keyboard::Keyboard::Key> keys;
 
-#ifdef LOVE_ANDROID
-	std::vector<love::audio::Source*> pausedSources;
-#endif
-
 }; // Event
 
 } // sdl