Fix doc on unix signal handlers

[aureshinite]

Hey,

The documentation "Calling Qt Functions From Unix Signal Handlers":http://qt-project.org/doc/qt-4.8/unix-signals.html contains a potential bug. The structures @struct sigaction hup, term;@

are initialized on the stack, and it can result later to a stack corruption. For instance, my main was basically

@int main(int argc, char* argv[]){

setup_unix_signal_handlers();
QApplication app(argc, argv);

MyWidget w;
w.show();

app.exec();

}@

I catched SIGTERM to call exit but it was crashing on some occasions. I later found through valgrind that it crashed on the release version of the app and not on the debug one.

[messi]

Have you tested it with the example from the doc?
Please provide the exact code, so that it can be confirmed.