Make buildDirectoryInitialized a Qt4Project specific signal again

And fix it to the old behaviour while at it.

Change-Id: Ifd786e085c621fb3cd59b98cc665d9e3c7fcce51
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>

src/plugins/qt4projectmanager/qt4buildconfiguration.cpp

@@ -309,11 +309,6 @@ void Qt4BuildConfiguration::emitQMakeBuildConfigurationChanged()
     emit qmakeBuildConfigurationChanged();
 }
 
-void Qt4BuildConfiguration::emitBuildDirectoryInitialized()
-{
-    emit buildDirectoryInitialized();
-}
-
 QStringList Qt4BuildConfiguration::configCommandLineArguments() const
 {
     QStringList result;