Remove QRegExp dependencies and mentions

Change-Id: I399f8980f56eda5d60b554aa942bf045ab91e0d6
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/corelib/io/qdir.cpp

@@ -2150,7 +2150,6 @@ bool QDir::match(const QStringList &filters, const QString &fileName)
 {
     for (QStringList::ConstIterator sit = filters.constBegin(); sit != filters.constEnd(); ++sit) {
         // Insensitive exact match
-        // (see Notes for QRegExp Users in QRegularExpression's documentation)
         QRegularExpression rx(QRegularExpression::wildcardToRegularExpression(*sit),
                               QRegularExpression::CaseInsensitiveOption);
         if (rx.match(fileName).hasMatch())

src/corelib/io/qdiriterator.cpp

@@ -93,7 +93,9 @@
 #include "qdir_p.h"
 #include "qabstractfileengine_p.h"
 
+#ifdef QT_BOOTSTRAPPED
 #include <QtCore/qregexp.h>
+#endif
 #include <QtCore/qset.h>
 #include <QtCore/qstack.h>
 #include <QtCore/qvariant.h>