This patch has also been contributed upstream, so will not be needed anymore
soon. Also automatically clear cached variables for new nanovdb location in
libs.
Building against the existing 3.1 libraries should continue to work, until
the precompiled libraries are committed for all platforms.
* Enable WebP by default.
* Update Windows for new library file names.
* Automatically clear outdated CMake cache variables when upgrading to new
libraries.
* Fix static library linking order issues on Linux for OpenEXR and OpenVDB.
Implemented by Ray Molenkamp, Sybren Stüvel and Brecht Van Lommel.
Ref T95206