gl_state: Skip null texture binds

glBindTextureUnit doesn't support null textures. Skip binding these.

src/video_core/renderer_opengl/gl_state.cpp

@@ -420,9 +420,13 @@ void OpenGLState::ApplyTextures() {
     const std::size_t size = std::size(textures);
     for (std::size_t i = 0; i < size; ++i) {
         if (UpdateValue(cur_state.textures[i], textures[i])) {
+            // BindTextureUnit doesn't support binding null textures, skip those binds.
+            // TODO(Rodrigo): Stop using null textures
+            if (textures[i] != 0) {
                 glBindTextureUnit(static_cast<GLuint>(i), textures[i]);
             }
         }
+    }
 }
 
 void OpenGLState::ApplySamplers() {