"xrepo install" command shows "vs not found" even when msvc toolchain is not used

[vspefs]

While installing package 'vulkan-hpp' from the official GitHub xmake repo, after downloading the package, xmake shows "vs not found!" and exits.
My computer doesn't have MSVC installed because I use clang/llvm toolchain.

[star-hengxing]

Xmake package only support clang-cl/msvc toolchain on Windows, and only cross plat (xmake f -p cross) support any toolchain.
Currently, most of the pre-compiled llvm toolchain depends on msvc stl + ucrt.

$ clang -v
Target: x86_64-pc-windows-msvc