GL: Check texture framebuffer feedback only if not using compute pipeline.

This was getting in the way in multiple instances. Compute shaders dispatch
are still made in the presence of the last bound framebuffer even if they
do not interact with it.

source/blender/gpu/opengl/gl_shader.hh

@@ -72,6 +72,11 @@ class GLShader : public Shader {
   /** DEPRECATED: Kept only because of BGL API. */
   int program_handle_get() const override;
 
+  bool is_compute() const
+  {
+    return compute_shader_ != 0;
+  }
+
  private:
   char *glsl_patch_get(GLenum gl_stage);
 

source/blender/gpu/opengl/gl_texture.cc

@@ -688,6 +688,11 @@ void GLTexture::check_feedback_loop()
   if (GPU_mip_render_workaround()) {
     return;
   }
+  /* Do not check if using compute shader. */
+  GLShader *sh = dynamic_cast<GLShader *>(Context::get()->shader);
+  if (sh && sh->is_compute()) {
+    return;
+  }
   GLFrameBuffer *fb = static_cast<GLFrameBuffer *>(GLContext::get()->active_fb);
   for (int i = 0; i < ARRAY_SIZE(fb_); i++) {
     if (fb_[i] == fb) {