[client] wayland: implement HDR support

client/include/app.h

@@ -72,6 +72,13 @@ void app_setFullscreen(bool fs);
 bool app_getFullscreen(void);
 bool app_getProp(LG_DSProperty prop, void * ret);
 
+/**
+ * Returns true if the last call to setHDRImageDescription() failed.
+ * When this returns true, the renderer should fall back to software
+ * tone-mapping even on a compositor that reports LG_DS_NATIVE_HDR.
+ */
+bool app_getHDRDescFailed(void);
+
 #ifdef ENABLE_EGL
 EGLDisplay app_getEGLDisplay(void);
 EGLNativeWindowType app_getEGLNativeWindow(void);