[llvm] [offload] Add Windows offload support (PR #187006)

[Michael Kruse via llvm-commits]

================
@@ -2,6 +2,16 @@
 set(common_dir ${CMAKE_CURRENT_SOURCE_DIR}/common)
 set(common_bin_dir ${CMAKE_CURRENT_BINARY_DIR}/common)
 add_subdirectory(common)
+
+# Only build specific plugins if any are requested
----------------
Meinersbur wrote:

I was expecting a dedicated PR if it can be separated out, so there is less to review in this PR.

Instead of `return ()` in `plugins-next/CMakeLists.txt` and meddling with the parent scope, prefer to not even `add_subdirectory(plugins-nextgen)`.

https://github.com/llvm/llvm-project/pull/187006