Avoid using unadjusted ABI for the thread-local shim

This restricts the uses of the unadjusted ABI to LLVM intrinsics. The
Rust ABI works fine for the thread-local shim as it always returns
pointers directly like the backend expects.

Author: bjorn3

compiler/rustc_ty_utils/src/abi.rs

@@ -39,7 +39,7 @@ fn fn_sig_for_fn_abi<'tcx>(
             tcx.thread_local_ptr_ty(instance.def_id()),
             false,
             hir::Safety::Safe,
-            rustc_abi::ExternAbi::Unadjusted,
+            rustc_abi::ExternAbi::Rust,
         );
     }