QDir: use QStringTokenizer

Avoids having to allocate storage to hold the parts.

Change-Id: Ie4d877af959751139f4c098b644e4a57f63d03b9
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qdir.cpp

@@ -177,10 +177,8 @@ inline QStringList QDirPrivate::splitFilters(const QString &nameFilter, QChar se
 {
     if (sep.isNull())
         sep = getFilterSepChar(nameFilter);
-    const auto split = QStringView{nameFilter}.split(sep);
     QStringList ret;
-    ret.reserve(split.size());
-    for (const auto &e : split)
+    for (auto e : qTokenize(nameFilter, sep))
         ret.append(e.trimmed().toString());
     return ret;
 }