async: fix reference initializer warning

Clang is unhappy about an initializer for a member reference, even
though the constructors properly initialize the value:

```
../include/sdbusplus/async/client.hpp:24:35: error: non-const lvalue reference to type 'sdbusplus::async::context' cannot bind to an initializer list temporary
```

Drop the `{}` so the member is uninitialized.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If1f12e8eac4913f0147f39157dd9c48d1803bb9e
diff --git a/include/sdbusplus/async/client.hpp b/include/sdbusplus/async/client.hpp
index 5290894..ce9fc24 100644
--- a/include/sdbusplus/async/client.hpp
+++ b/include/sdbusplus/async/client.hpp
@@ -21,7 +21,7 @@
     public Types<sdbusplus::async::proxy_ns::proxy<S, P, false, Preserved>>...
 {
   private:
-    sdbusplus::async::context& ctx{};
+    sdbusplus::async::context& ctx;
     sdbusplus::async::proxy_ns::proxy<S, P, false, Preserved> proxy{};
 
   public:
diff --git a/tools/sdbusplus/templates/interface.client.hpp.mako b/tools/sdbusplus/templates/interface.client.hpp.mako
index b6c3777..ae49f10 100644
--- a/tools/sdbusplus/templates/interface.client.hpp.mako
+++ b/tools/sdbusplus/templates/interface.client.hpp.mako
@@ -76,7 +76,7 @@
         ctx(ctx), proxy(p.interface(interface))
     {}
 
-    sdbusplus::async::context& ctx{};
+    sdbusplus::async::context& ctx;
     decltype(std::declval<Proxy>().interface(interface)) proxy = {};
 };