[LyX/master] Qt6 QFontDatabase is a pure static class. Call the member functions directly.

[Stephan Witt]

commit 21258638744d5efa24b1a776daeff1fff1abe6d5
Author: Stephan Witt <switt at lyx.org>
Date:   Sat Jan 1 10:06:07 2022 +0100

    Qt6 QFontDatabase is a pure static class. Call the member functions directly.
---
 src/frontends/qt/GuiDocument.cpp |    6 +++++-
 src/frontends/qt/GuiPrefs.cpp    |    6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/frontends/qt/GuiDocument.cpp b/src/frontends/qt/GuiDocument.cpp
index 3e6df5d..4067d6c 100644
--- a/src/frontends/qt/GuiDocument.cpp
+++ b/src/frontends/qt/GuiDocument.cpp
@@ -2679,8 +2679,12 @@ void GuiDocument::updateFontlist()
 		fontModule->fontsMathCO->addItem(qt_("Class Default (TeX Fonts)"), QString("auto"));
 		fontModule->fontsMathCO->addItem(unimath, QString("default"));
 
+#if QT_VERSION >= 0x060000
+		const QStringList families(QFontDatabase::families());
+#else
 		QFontDatabase fontdb;
-		QStringList families(fontdb.families());
+		const QStringList families(fontdb.families());
+#endif
 		for (auto const & family : families) {
 			fontModule->fontsRomanCO->addItem(family, family);
 			fontModule->fontsSansCO->addItem(family, family);
diff --git a/src/frontends/qt/GuiPrefs.cpp b/src/frontends/qt/GuiPrefs.cpp
index 75deb7c..40c0638 100644
--- a/src/frontends/qt/GuiPrefs.cpp
+++ b/src/frontends/qt/GuiPrefs.cpp
@@ -931,8 +931,12 @@ PrefScreenFonts::PrefScreenFonts(GuiPreferences * form)
 		this, SLOT(selectTypewriter(QString)));
 #endif
 
+#if QT_VERSION >= 0x060000
+	const QStringList families(QFontDatabase::families());
+#else
 	QFontDatabase fontdb;
-	QStringList families(fontdb.families());
+	const QStringList families(fontdb.families());
+#endif
 	for (auto const & family : families) {
 		screenRomanCO->addItem(family);
 		screenSansCO->addItem(family);