Change the way libunwind is linked for *-windows-gnullvm targets

library/unwind/src/lib.rs

@@ -104,7 +104,3 @@ extern "C" {}
 #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
 #[link(name = "unwind", kind = "static", modifiers = "-bundle")]
 extern "C" {}
-
-#[cfg(all(target_os = "windows", target_env = "gnu", target_abi = "llvm"))]
-#[link(name = "unwind", kind = "static", modifiers = "-bundle")]
-extern "C" {}

library/unwind/src/libunwind.rs

@@ -90,7 +90,10 @@ pub type _Unwind_Exception_Cleanup_Fn =
 // rustc_codegen_ssa::src::back::symbol_export, rustc_middle::middle::exported_symbols
 // and RFC 2841
 #[cfg_attr(
-    all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
+    any(
+        all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
+        all(target_os = "windows", target_env = "gnu", target_abi = "llvm")
+    ),
     link(name = "unwind", kind = "static", modifiers = "-bundle")
 )]
 extern "C-unwind" {

src/bootstrap/compile.rs

@@ -206,7 +206,6 @@ fn copy_third_party_objects(
     }
 
     if target == "x86_64-fortanix-unknown-sgx"
-        || target.contains("pc-windows-gnullvm")
         || builder.config.llvm_libunwind(target) == LlvmLibunwind::InTree
             && (target.contains("linux") || target.contains("fuchsia"))
     {