[Bug 45696] iconcache ImageList goes out of sync when an icon partially fails to load

https://bugs.winehq.org/show_bug.cgi?id=45696

--- Comment #1 from Gabriel Ivăncescu  ---
Created attachment 62900
  --> https://bugs.winehq.org/attachment.cgi?id=62900
Generate icons from available icons if some icon sizes failed to load

Commit 4e633f92442a7e45add37e82a07d848a5c13164b fixes the out of sync problem,
but the icon won't be loaded in this case (it's still far better, though). This
patch implements the workaround of generating the icon from another one that
succeeded to load. It's done empirically only and a semi-hack, to make it less
pixelated, but it should be alright for a workaround, for now.