Support family names that end/start with space

If the family name starts or ends with a space in the actual font
data, then this would not be selectable by Qt. This is because we trim
the family name before matching it against the contents of the database.

Testing on Windows GDI, it actually does trim the spaces on the
family names (matching a request for "Chibola" with a font called
"Chibola " for instance), but since we read the font data ourselves,
we are not doing this.

To ensure we never have font names that cannot be matched in the
database, we make sure we trim the family names before registering
them.

[ChangeLog][QtGui][Text] Fixed matching against fonts which has a
family name that ends or starts with a space.

Task-number: QTBUG-79140
Pick-to: 6.1
Pick-to: 6.0
Pick-to: 5.15
Change-Id: I9cdb50b78a7da2d2697f992ce462033eb1d7ada7
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

src/gui/text/qfontdatabase.cpp

@@ -304,10 +304,12 @@ void QFontDatabasePrivate::invalidate()
     emit static_cast<QGuiApplication *>(QCoreApplication::instance())->fontDatabaseChanged();
 }
 
-QtFontFamily *QFontDatabasePrivate::family(const QString &f, FamilyRequestFlags flags)
+QtFontFamily *QFontDatabasePrivate::family(const QString &family, FamilyRequestFlags flags)
 {
     QtFontFamily *fam = nullptr;
 
+    const QString f = family.trimmed();
+
     int low = 0;
     int high = count;
     int pos = count / 2;