[clang] [llvm] [OpenMP] Remove 'libomptarget.devicertl.a' fatbinary and use static library (PR #126143)

[Michał Górny via llvm-commits]

mgorny wrote:

No, I'm afraid that didn't change anything. However, it did if I added it to `target_link_options` too.

That said, you want to instead:

```diff
--- a/offload/DeviceRTL/CMakeLists.txt
+++ b/offload/DeviceRTL/CMakeLists.txt
@@ -132,7 +132,7 @@ function(compileDeviceRTLLibrary target_name target_triple)
     BUILD_RPATH ""
     INSTALL_RPATH ""
     RUNTIME_OUTPUT_NAME libomptarget-${target_name}.bc)
-  target_compile_options(libomptarget-${target_name} PRIVATE "--target=${target_triple}")
+  target_compile_options(libomptarget-${target_name} PRIVATE "--target=${target_triple}" "-march=")
   target_link_options(libomptarget-${target_name} PRIVATE "--target=${target_triple}"
-                      "-r" "-nostdlib" "-flto" "-Wl,--lto-emit-llvm")
+                      "-r" "-nostdlib" "-flto" "-Wl,--lto-emit-llvm" "-march=")
   install(TARGETS libomptarget-${target_name}
```

without the `''` since that gets passed literally, and triggers warnings about `''` being an invalid target :-).

https://github.com/llvm/llvm-project/pull/126143