Merge two operations that were always performed together

compiler/rustc_codegen_llvm/src/llvm/mod.rs

@@ -409,3 +409,9 @@ pub(crate) fn set_dllimport_storage_class<'ll>(v: &'ll Value) {
         LLVMSetDLLStorageClass(v, DLLStorageClass::DllImport);
     }
 }
+
+pub(crate) fn set_dso_local<'ll>(v: &'ll Value) {
+    unsafe {
+        LLVMRustSetDSOLocal(v, true);
+    }
+}