storagehelper: avoid using QFontDatabase

Change-Id: Ia5045de44b598d2b0c8d813436b8574b54aeb1a9

src/authority/storagehelper.cpp

@@ -151,7 +151,10 @@ QString
 compressedAvatar(const QString& image)
 {
     QImage qimage;
-    const bool ret = qimage.loadFromData(QByteArray::fromBase64(image.toUtf8()), 0);
+    // Avoid to use all formats. Some seems bugguy, like libpbf, asking
+    // for a QGuiApplication for QFontDatabase
+    auto ret = qimage.loadFromData(QByteArray::fromBase64(image.toUtf8()), "JPEG");
+    if (!ret) ret = qimage.loadFromData(QByteArray::fromBase64(image.toUtf8()), "PNG");
     if (!ret) {
         qDebug() << "vCard image loading failed";
         return image;