BuildConfiugration::subConfigWidge() Provide a default implementation

Which simply returns a BuildEnvironmentWidget. A long time ago
BuildConfigurations had no environment, nowdays they do. So it makes
sense for all BuildConfigurations to have the BuildEnvironmentWidget.

Change-Id: I824c45df79a0dcd2b624bf67a4730fb5dab098bc
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.cpp

@@ -33,7 +33,6 @@
 #include "cmakeproject.h"
 #include "cmakeprojectconstants.h"
 
-#include <projectexplorer/buildenvironmentwidget.h>
 #include <projectexplorer/buildsteplist.h>
 #include <projectexplorer/gnumakeparser.h>
 #include <projectexplorer/ioutputparser.h>
@@ -112,14 +111,6 @@ ProjectExplorer::BuildConfigWidget *CMakeBuildConfiguration::createConfigWidget(
     return new CMakeBuildSettingsWidget;
 }
 
-QList<ProjectExplorer::BuildConfigWidget *> CMakeBuildConfiguration::subConfigWidgets()
-{
-    QList<ProjectExplorer::BuildConfigWidget*> list;
-    list << new ProjectExplorer::BuildEnvironmentWidget;
-    return list;
-}
-
-
 QString CMakeBuildConfiguration::buildDirectory() const
 {
     return m_buildDirectory;

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -52,7 +52,6 @@ public:
     ~CMakeBuildConfiguration();
 
     ProjectExplorer::BuildConfigWidget *createConfigWidget();
-    QList<ProjectExplorer::BuildConfigWidget *> subConfigWidgets();
     QString buildDirectory() const;
 
     void setBuildDirectory(const QString &buildDirectory);