Please resurrect slotBuild() in trollprojectpart

[Stephan Diederich]

problem:
If the debugger detects a changed project it asks the user to rebuild.
Pushing Yes does nothing for qmake projects.

The reason seems to be a commented slotBuild() method in
TrollProjectPart, which the debugger wants to use (debuggerpart.cpp
Line 878)

Following method would solve the problem:
void TrollProjectPart::slotBuild(){
    m_widget->slotBuildProject();
}

Cheers,
Stephan