GL: Remove lingering image binds

This updates image bind tracking to be the same as texture binds.
Adding a new bind flag to avoid conflict when the texture is used in
both slots.
Fixes a gl error in glBindImageTextures about invalid image binds.

source/blender/gpu/opengl/gl_state.cc

@@ -563,14 +563,14 @@ void GLStateManager::image_bind(Texture *tex_, int unit)
   }
   images_[unit] = tex->tex_id_;
   formats_[unit] = to_gl_internal_format(tex->format_);
-  tex->is_bound_ = true;
+  tex->is_bound_image_ = true;
   dirty_image_binds_ |= 1ULL << unit;
 }
 
 void GLStateManager::image_unbind(Texture *tex_)
 {
   GLTexture *tex = static_cast<GLTexture *>(tex_);
-  if (!tex->is_bound_) {
+  if (!tex->is_bound_image_) {
     return;
   }
 
@@ -581,7 +581,7 @@ void GLStateManager::image_unbind(Texture *tex_)
       dirty_image_binds_ |= 1ULL << i;
     }
   }
-  tex->is_bound_ = false;
+  tex->is_bound_image_ = false;
 }
 
 void GLStateManager::image_unbind_all()

source/blender/gpu/opengl/gl_texture.cc

@@ -40,6 +40,7 @@ GLTexture::~GLTexture()
   if (ctx != nullptr && is_bound_) {
     /* This avoid errors when the texture is still inside the bound texture array. */
     ctx->state_manager->texture_unbind(this);
+    ctx->state_manager->image_unbind(this);
   }
   GLContext::tex_free(tex_id_);
 }

source/blender/gpu/opengl/gl_texture.hh

@@ -37,6 +37,8 @@ class GLTexture : public Texture {
   /** True if this texture is bound to at least one texture unit. */
   /* TODO(fclem): How do we ensure thread safety here? */
   bool is_bound_ = false;
+  /** Same as is_bound_ but for image slots. */
+  bool is_bound_image_ = false;
   /** True if pixels in the texture have been initialized. */
   bool has_pixels_ = false;