async: scope: constructor fix to make clang happy

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I339a65278c2a540d1235db436b95b80ff222d932
diff --git a/include/sdbusplus/async/scope.hpp b/include/sdbusplus/async/scope.hpp
index 06a30d7..8975194 100644
--- a/include/sdbusplus/async/scope.hpp
+++ b/include/sdbusplus/async/scope.hpp
@@ -229,6 +229,8 @@
     {
         return ((Fn&&)fn)();
     }
+
+    explicit in_place_construct(Fn&& fn) : fn(std::move(fn)){};
 };
 
 } // namespace scope_ns