58518347f2
Part of #118145. Change the "Pivot to Unmasked" and "Pivot to Mask Border" operations to avoid the vertex iteration macro. The former also uses a proper weighted average now, so mostly-masked vertices have less influence. The whole operation is multithreaded now so I expect it's a bit faster, but I didn't explicitly test that. Pull Request: https://projects.blender.org/blender/blender/pulls/124743