Windows CMake install target fails

[lunarpapillo]

Description
The (experimental) CMake build process fails with the install target when trying to install llvm-as (which was never built).

Steps to Reproduce

cmake -H. -Bbuild -G "Visual Studio 16" -Ax64 -DCMAKE_INSTALL_PREFIX=install -C cmake\caches\PredefinedParams.cmake
cmake --build build
cmake --build --target install

Actual Behavior
The install target fails with:

  CMake Error at tools/llvm-as/cmake_install.cmake:43 (file):
    file INSTALL cannot find
    "C:/Users/lunarg/work/microsoft/DirectXShaderCompiler/build/RelWithDebInfo/bin/llvm-as.exe":
    File exists.
  Call Stack (most recent call first):
    tools/cmake_install.cmake:47 (include)
    cmake_install.cmake:117 (include)

Environment

• DXC version : n/a, using commit 93ad5b3 , which is currently HEAD on main
• Host Operating System: Windows 10

[llvm-beanz]

This is a duplicate of:

#5682

We've never used the install action so it doesn't work.