Merge #797: qml: Add default member initializers to QmlCoreSettings::Values strings

cb3351c qml: Add default member initializers to `QmlCoreSettings::Values` strings (Hennadii Stepanov)

Pull request description:

  Silences GCC's `-Wmissing-field-initializers` at designated-initializer call sites in `test_options_model.cpp`, where only `proxy_address` and `tor_address` were flagged as they were the only members without a default member initializer.

  Fixes #779.

ACKs for top commit:
  johnny9:
    ACK cb3351c

Tree-SHA512: 355aad1b1c640df853bc6f8478dc4b305f83c83705ebba02a4485da24cba21a085d9eee851649fb193038d8ac27144faa2518c7e5a08a2de1611e707f1ec3f71

Author: hebasto

qml/core_settings.h

@@ -28,9 +28,9 @@ struct Values {
     bool natpmp{false};
     bool server{false};
     bool proxy_enabled{false};
-    QString proxy_address;
+    QString proxy_address{};
     bool tor_enabled{false};
-    QString tor_address;
+    QString tor_address{};
 };
 
 struct Change {