Compiling with HP-UX is very interesting effort, thanks!
Recently there was trouble as we forgot to export makefiles before release, but that should be fixed now (as of beta4). (QtfCtrl.cpp was removed from the source tree).
I am quite puzzled, I have just checked it by searching Makefile for "QtfCtrl" and found nothing. Are you sure it is beta4? (However, I checked from the folder here, I will try to download and unpack from sf.net).
As for chances that it will run on HP-UX - one possible limitation is that U++ now requires Xft / XRender - without them chances are dim... (there is old XLFD font rendering path, but it was not tested for some time now and will not be supported anymore).