Heretic: update P_GroupLines and (re-)create BLOCKMAP if necessary

[JNechaevsky]

As always, few remarks:

• I believe old P_GroupLines code is from Doom 1.2, as according DoomWiki, Heretic itself is based on Doom 1.2.
• Comment about "...from Chocolate Doom" is deliberately, as released source code Doom 1.10 have minimal difference in P_GroupLines (notably, Z_Malloc).
• I have slightly changed final printf in P_CreateBlockMap and excluded printf below this line to better match of Crispy Heretic printfs since there is no "better logging" like in Crispy Doom.
• That testing map15 (replacement for E1M1) is still a thing. Now it is loading fast and hitscans no longer crashing the game in wide areas. Free noclip walking through the map is still dangerous for performance. After porting Pr+ de-facto optimizations few times, I can only say it's not that complicated, but the diff is not that small as well. It was discussed before, so it is out of question, of course.
• All SM Speed world records demos from dsdarchive.com have successfully passed -timedemo runs. All of them are all recorded under DSDA.
• Only spaces and not tabs in replaced Heretic's code, and as small diff as possible. ☝️

[fabiangreffrath]

Great improvement, thank you!

[JNechaevsky]

Actually... I was thinking to ask you and @rfomin for small recommendation, and as always totally forgot about it. 🙂
It's very simple. When I need to see how much time any function is taking, I'm adding two such lines to the function, like:

void P_SlowFunction (void)
{
    const int starttime = SDL_GetTicks();

    ...

    printf("executed in %d ms.\n", SDL_GetTicks() - starttime)
}

It is working perfectly fine and having milliseconds is all what is really needed. But it requies SDL.h header to be provided. So I would like to ask, is there any possible way to make it simpler? Probably, macrocized somewhere in upper level's header file, which already have SDL.h file included? Or is there a better way to gather such execution time?

[fabiangreffrath]

You won't get away without including any headers, but SDL is surely a heavy-weight. Here's an implementation I used to benchmark different openal-soft backends:

kcat/openal-soft#930

[rfomin]

You should have I_GetTimeMS() which is the same as SDL_GetTicks(). It's in i_timer.h.

You also have the microsecond precision timer I_GetTimeUS(), it's much better for measuring the runtime of functions.

[JNechaevsky]

Oh, this really will cover all possible needs, I even have to investigate how to use all these functions more or less properly.

Thanks very much!