Merge bitcoin#16758: qt: Replace QFontMetrics::width() with TextWidth()

8b6f5aa qt: Replace QFontMetrics::width() with TextWidth() (Hennadii Stepanov)

Pull request description:

  Compiling master (d8fc997) on macOS Catalina (with a patch from bitcoin#16720) reveals one more instance of `QFontMetrics::width()` which is supposed to be replaced with `TextWidth()` in the merged bitcoin#16701.

  Sorry for incomplete solution provided in bitcoin#16701. It’s especially sad that the line I missed lies in only 7 lines from the code touched in bitcoin#16701.

ACKs for top commit:
  fanquake:
    ACK 8b6f5aa

Tree-SHA512: 65cd8bea550150e5ee47c1e906d8c2393547cf4feba3701a933a4f24fad5ecdb552ac2de4e1200ed14efaa0df0480150dd58fccbddc3b902f6c2141603874902

Author: fanquake

src/qt/guiutil.cpp

@@ -947,7 +947,7 @@ void PolishProgressDialog(QProgressDialog* dialog)
 {
 #ifdef Q_OS_MAC
     // Workaround for macOS-only Qt bug; see: QTBUG-65750, QTBUG-70357.
-    const int margin = dialog->fontMetrics().width("X");
+    const int margin = TextWidth(dialog->fontMetrics(), ("X"));
     dialog->resize(dialog->width() + 2 * margin, dialog->height());
     dialog->show();
 #else