gltfpack: Fix texture compression spawn on Windows
gltfpack: Fix texture compression spawn on Windows

When using native Windows builds and using TOKTX_PATH or BASISU_PATH
that had spaces in them, gltfpack didn't automatically quote these,
resulting in the executable not being runnable.

We now automatically quote paths on Windows that have spaces in them to
fix this.

zeux/meshoptimizer,zeux/meshoptimizer,zeux/meshoptimizer