HostOsInfo/FileUtils/PersistentSettings: Fix build without QtGui

Interesting for command line tools that want to pull this in but not
QtGui (e.g. sdktool)

Change-Id: Ic2f5c1f3126869cc38bf672345750d7d966560fd
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

src/libs/utils/fileutils.cpp

@@ -29,14 +29,18 @@
 #include "algorithm.h"
 #include "qtcassert.h"
 
+#include <QDataStream>
 #include <QDir>
 #include <QDebug>
 #include <QDateTime>
-#include <QMessageBox>
 #include <QRegExp>
 #include <QTimer>
 #include <QUrl>
 
+#ifdef QT_GUI_LIB
+#include <QMessageBox>
+#endif
+
 #ifdef Q_OS_WIN
 #include <qt_windows.h>
 #include <shlobj.h>
@@ -378,6 +382,7 @@ bool FileReader::fetch(const QString &fileName, QIODevice::OpenMode mode, QStrin
     return false;
 }
 
+#ifdef QT_GUI_LIB
 bool FileReader::fetch(const QString &fileName, QIODevice::OpenMode mode, QWidget *parent)
 {
     if (fetch(fileName, mode))
@@ -386,7 +391,7 @@ bool FileReader::fetch(const QString &fileName, QIODevice::OpenMode mode, QWidge
         QMessageBox::critical(parent, tr("File Error"), m_errorString);
     return false;
 }
-
+#endif // QT_GUI_LIB
 
 FileSaverBase::FileSaverBase()
     : m_hasError(false)
@@ -412,6 +417,7 @@ bool FileSaverBase::finalize(QString *errStr)
     return false;
 }
 
+#ifdef QT_GUI_LIB
 bool FileSaverBase::finalize(QWidget *parent)
 {
     if (finalize())
@@ -419,6 +425,7 @@ bool FileSaverBase::finalize(QWidget *parent)
     QMessageBox::critical(parent, tr("File Error"), errorString());
     return false;
 }
+#endif // QT_GUI_LIB
 
 bool FileSaverBase::write(const char *data, int len)
 {