Rename config.host_os to config.target_os.

config.host_os is derived from CMAKE_SYSTEM_NAME
which specifies the target. See:
https://cmake.org/cmake/help/latest/variable/CMAKE_SYSTEM_NAME.html

To reduce confusion, rename it to config.target_os.

The variable name config.target_os was already being used by the Orc
tests. Rename it to config.orc_test_target_os with a FIXME to remove.

Reviewers: JDevlieghere, MaskRay

Reviewed By: MaskRay

Pull Request: https://github.com/llvm/llvm-project/pull/149015

GitOrigin-RevId: 3fa07ed5b38774656a2cff1bebc1785ce8e7feb8
35 files changed