Backport: 32-bit Windows build and runtime fixes for NGL and Vulkan

Hi,

This backports directly the recent fixes for 32-bit Windows for the stable gtk-4-14 branch, as the stable branch is affected as well:

• MR !7294 (merged) (Fix the NGL renderer running on 32-bit Windows)
• MR !7299 (merged) (Fix building the Vulkan renderer code on 32-bit Windows, and possibly other non-64-bit, non-LLP systems)

With blessings, thank you!