Fix colobot-lint warnings

src/graphics/opengl/gldevice.h

@@ -250,7 +250,7 @@ private:
     //! Set of all created textures
     std::set<Texture> m_allTextures;
     //! White texture
-    GLuint m_whiteTexture;
+    GLuint m_whiteTexture = 0;
 
     //! Map of framebuffers
     std::map<std::string, std::unique_ptr<CFramebuffer>> m_framebuffers;