Bump the minimum Qt version to 5.2

src/qt/guiutil.cpp

@@ -47,6 +47,7 @@
 #include <QDoubleValidator>
 #include <QFileDialog>
 #include <QFont>
+#include <QFontDatabase>
 #include <QKeyEvent>
 #include <QLineEdit>
 #include <QSettings>
@@ -55,11 +56,6 @@
 #include <QUrlQuery>
 #include <QMouseEvent>
 
-
-#if QT_VERSION >= 0x50200
-#include <QFontDatabase>
-#endif
-
 #if defined(Q_OS_MAC)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
@@ -82,13 +78,7 @@ QString dateTimeStr(qint64 nTime)
 
 QFont fixedPitchFont()
 {
-#if QT_VERSION >= 0x50200
     return QFontDatabase::systemFont(QFontDatabase::FixedFont);
-#else
-    QFont font("Monospace");
-    font.setStyleHint(QFont::Monospace);
-    return font;
-#endif
 }
 
 // Just some dummy data to generate a convincing random-looking (but consistent) address