Merge bitcoin#1057: [UI] Fix AA_EnableHighDpiScaling warning

9b8955a Fix AA_EnableHighDpiScaling warning (Akshay)

Pull request description:

  Fixes the following warning

  `Attribute Qt::AA_EnableHighDpiScaling must be set before QCoreApplication is created.`

  Tested on macOS 10.14.6

ACKs for top commit:
  furszy:
    ACK 9b8955a
  random-zebra:
    utACK 9b8955a and merging...

Tree-SHA512: f65b10f570bd642da9428e634c89bfe6303ccbeb1f3995c85993845c86a321dccb1f50cdd39832e4c2e910942f0b284944bd88cd181cf7a15fc46279e30e22b3

src/qt/pivx.cpp

@@ -529,7 +529,6 @@ int main(int argc, char* argv[])
     Q_INIT_RESOURCE(pivx_locale);
     Q_INIT_RESOURCE(pivx);
 
-    BitcoinApplication app(argc, argv);
 #if QT_VERSION > 0x050100
     // Generate high-dpi pixmaps
     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
@@ -540,6 +539,7 @@ int main(int argc, char* argv[])
 #ifdef Q_OS_MAC
     QApplication::setAttribute(Qt::AA_DontShowIconsInMenus);
 #endif
+    BitcoinApplication app(argc, argv);
 
     // Register meta types used for QMetaObject::invokeMethod
     qRegisterMetaType<bool*>();