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 * Automatically clear outdated CMake cache variables when upgrading to new libraries.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