trivial: squash missing field 'argNames' initializer warning in qt tests

The additional initializer is for the named arguments, which are unused
in the test (and unfilled global fields will be initialized to 0
anyhow), so this is a no-op apart from the warning.

src/qt/test/rpcnestedtests.cpp

@@ -29,7 +29,7 @@ static UniValue rpcNestedTest_rpc(const JSONRPCRequest& request)
 
 static const CRPCCommand vRPCCommands[] =
 {
-    { "test", "rpcNestedTest", &rpcNestedTest_rpc, true },
+    { "test", "rpcNestedTest", &rpcNestedTest_rpc, true, {} },
 };
 
 void RPCNestedTests::rpcNestedTests()