Remove unused exception parameter from files inc dynolog/src/rpc/Simp…

…leJsonServerInl.h (#204)

Summary:
Pull Request resolved: #204

`-Wunused-exception-parameter` has identified an unused exception parameter. This diff removes it.

This:
```
try {
    ...
} catch (exception& e) {
    // no use of e
}
```
should instead be written as
```
} catch (exception&) {
```

If the code compiles, this is safe to land.

Reviewed By: dmm-fb

Differential Revision: D51977808

fbshipit-source-id: 615639c2db7d63fbac33e3a3a4317b48dbc869d1

dynolog/src/rpc/SimpleJsonServerInl.h

@@ -38,7 +38,7 @@ nlohmann::json toJson(const std::string& message) {
   }
   try {
     result = json::parse(message);
-  } catch (json::parse_error& ex) {
+  } catch (json::parse_error&) {
     LOG(ERROR) << "Error parsing message = " << message;
     return result;
   }