This is a workaround for an upstream LLVM issue [0], which looks to be
caused by the `CMAKE_INSTALL_LIBDIR` variable is used before
definition.  While there is an LLVM PR to resolve this fix [1], as of
2024-08-19 it has not yet been merged to LLVM.

This change is intended to resolve the following error, which occurs
during the CI build of TVM on Windows.

```
The system cannot find the file specified.
CMake Error at C:/Miniconda/envs/tvm-build/conda-bld/tvm-package_1723747883202/_h_env/Library/lib/cmake/llvm/Findzstd.cmake:39 (string):
  string sub-command REGEX, mode REPLACE: regex "$" matched an empty string.
Call Stack (most recent call first):
  C:/Miniconda/envs/tvm-build/conda-bld/tvm-package_1723747883202/_h_env/Library/lib/cmake/llvm/LLVMConfig.cmake:277 (find_package)
  cmake/utils/FindLLVM.cmake:47 (find_package)
  cmake/modules/LLVM.cmake:31 (find_llvm)
  CMakeLists.txt:565 (include)
```

[0] llvm/llvm-project#83802
[1] llvm/llvm-project#83807

If pytest captures the output, segfaults in a unit test prevent any
output from being printed.

The f32-to-f32 test case passed, so it's not an issue with
all generated code.  Trying a f16-to-f16 conversion to see if it's a
problem with the existence of f16 arguments at all.