Make compilable with 5.11

While it is understood that there won't be any further release from
this 4.2 branch, it helps with bisecting Qt Creator when there isn't
a need to build a contemporary Qt version as well.

Change-Id: Icb722ca45f4a70b73a9a4932a103ae8e45b500a0
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/qmleditorwidgets/contextpanewidgetimage.cpp

@@ -37,6 +37,7 @@
 #include <QMouseEvent>
 #include <QScrollArea>
 #include <QSlider>
+#include <QStyle>
 #include <QToolButton>
 #include <QDebug>
 

src/plugins/coreplugin/dialogs/readonlyfilesdialog.cpp

@@ -36,6 +36,7 @@
 #include <utils/fileutils.h>
 #include <utils/hostosinfo.h>
 
+#include <QButtonGroup>
 #include <QDir>
 #include <QFileInfo>
 #include <QMap>

src/plugins/coreplugin/find/findtoolbar.cpp

@@ -47,6 +47,7 @@
 #include <QDebug>
 #include <QSettings>
 
+#include <QAbstractItemView>
 #include <QCheckBox>
 #include <QClipboard>
 #include <QCompleter>

src/plugins/macros/macrooptionswidget.cpp

@@ -35,6 +35,7 @@
 #include <coreplugin/actionmanager/command.h>
 #include <coreplugin/id.h>
 
+#include <QAction>
 #include <QDir>
 #include <QFileInfo>
 #include <QTreeWidget>

src/plugins/projectexplorer/devicesupport/desktopdeviceconfigurationwidget.cpp

@@ -31,6 +31,8 @@
 #include <utils/portlist.h>
 #include <utils/qtcassert.h>
 
+#include <QRegExpValidator>
+
 using namespace ProjectExplorer::Constants;
 
 namespace ProjectExplorer {

src/tools/qtcreatorcrashhandler/crashhandlerdialog.cpp

@@ -34,6 +34,7 @@
 #include <QClipboard>
 #include <QIcon>
 #include <QSettings>
+#include <QStyle>
 
 static const char SettingsApplication[] = "QtCreator";
 static const char SettingsKeySkipWarningAbortingBacktrace[]