QmakePM: Remove unused private function

Change-Id: I2b7c0eda487495151616bf91211effd92c078a40
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>

src/plugins/qmakeprojectmanager/qmakebuildconfiguration.cpp

@@ -186,13 +186,6 @@ NamedWidget *QmakeBuildConfiguration::createConfigWidget()
     return new QmakeProjectConfigWidget(this);
 }
 
-QString QmakeBuildConfiguration::defaultShadowBuildDirectory() const
-{
-    // todo displayName isn't ideal
-    return shadowBuildDirectory(target()->project()->projectFilePath().toString(),
-                                target()->kit(), displayName());
-}
-
 /// If only a sub tree should be build this function returns which sub node
 /// should be build
 /// \see QMakeBuildConfiguration::setSubNodeBuild

src/plugins/qmakeprojectmanager/qmakebuildconfiguration.h

@@ -127,7 +127,6 @@ protected:
 
 private:
     void ctor();
-    QString defaultShadowBuildDirectory() const;
 
     class LastKitState
     {