Overhaul platform and decoder/renderer detection

app/streaming/audio.cpp

@@ -127,7 +127,7 @@ int Session::sdlAudioInit(int /* audioConfiguration */,
     // pending data count. Get a baseline so we
     // can exclude that data.
     s_BaselinePendingData = 0;
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
     for (int i = 0; i < 100; i++) {
         s_BaselinePendingData = qMax(s_BaselinePendingData, SDL_GetQueuedAudioSize(s_AudioDevice));
         SDL_Delay(10);

app/streaming/session.cpp

@@ -82,6 +82,7 @@ bool Session::chooseDecoder(StreamingPreferences::VideoDecoderSelection vds,
                             SDL_Window* window, int videoFormat, int width, int height,
                             int frameRate, IVideoDecoder*& chosenDecoder)
 {
+#ifdef HAVE_FFMPEG
     chosenDecoder = new FFmpegVideoDecoder();
     if (chosenDecoder->initialize(vds, window, videoFormat, width, height, frameRate)) {
         SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
@@ -94,6 +95,7 @@ bool Session::chooseDecoder(StreamingPreferences::VideoDecoderSelection vds,
         delete chosenDecoder;
         chosenDecoder = nullptr;
     }
+#endif
 
     // If we reach this, we didn't initialize any decoders successfully
     return false;

app/streaming/video/ffmpeg.cpp

@@ -1,13 +1,15 @@
 #include <Limelight.h>
 #include "ffmpeg.h"
 
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
 #include "ffmpeg-renderers/dxva2.h"
 #endif
 
-#ifdef __APPLE__
+#ifdef Q_OS_DARWIN
 #include "ffmpeg-renderers/vt.h"
-#elif defined Q_OS_UNIX
+#endif
+
+#ifdef HAVE_LIBVA
 #include "ffmpeg-renderers/vaapi.h"
 #endif
 
@@ -62,16 +64,17 @@ bool FFmpegVideoDecoder::chooseDecoder(
 
         // Look for acceleration types we support
         switch (config->device_type) {
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
         case AV_HWDEVICE_TYPE_DXVA2:
             newRenderer = new DXVA2Renderer();
             break;
 #endif
-#ifdef __APPLE__
+#ifdef Q_OS_DARWIN
         case AV_HWDEVICE_TYPE_VIDEOTOOLBOX:
             newRenderer = VTRendererFactory::createRenderer();
             break;
-#elif defined Q_OS_UNIX
+#endif
+#ifdef HAVE_LIBVA
         case AV_HWDEVICE_TYPE_VAAPI:
             newRenderer = new VAAPIRenderer();
             break;