Introduce a new FFMPEG frontend renderer: EGLRenderer

Right now this renderer works on X11 & Wayland with VAAPI as a backend.

Some rendering latency benchmarks on my `i7-10510U` (with
`intel-media-driver` 20.1.1 which cause a *huge* regression with the
SDL_Renderer):
|             | X11    | Wayland |
| Before      | 6.78ms | 22.50ms |
| EGLRenderer | 0.76ms | 00.77ms |

Signed-off-by: Antoine Damhet <antoine.damhet@lse.epita.fr>

app/streaming/video/ffmpeg-renderers/vaapi.h

@@ -26,6 +26,9 @@ extern "C" {
 #include <va/va_drm.h>
 #endif
 #include <libavutil/hwcontext_vaapi.h>
+#ifdef HAVE_EGL
+#include <va/va_drmcommon.h>
+#endif
 }
 
 class VAAPIRenderer : public IFFmpegRenderer
@@ -39,6 +42,12 @@ public:
     virtual bool needsTestFrame() override;
     virtual bool isDirectRenderingSupported() override;
     virtual int getDecoderColorspace() override;
+#ifdef HAVE_EGL
+    virtual bool canExportEGL() override;
+    virtual bool initializeEGL(EGLDisplay dpy, const EGLExtensions &ext);
+    virtual ssize_t exportEGLImages(AVFrame *frame, EGLDisplay dpy, EGLImage images[EGL_MAX_PLANES]) override;
+    virtual void freeEGLImages(EGLDisplay dpy, EGLImage[EGL_MAX_PLANES]) override;
+#endif
 
 private:
     bool validateDriver(VADisplay display);
@@ -57,4 +66,9 @@ private:
     int m_VideoHeight;
     int m_DisplayWidth;
     int m_DisplayHeight;
+
+#ifdef HAVE_EGL
+    VADRMPRIMESurfaceDescriptor m_PrimeDescriptor;
+    bool m_EGLExtDmaBuf;
+#endif
 };