[VanillaRA] Aftermath units in Skirmish mode are always disabled

[Gerwin2k]

Being unsure of it being an issue or my limited knowledge, I started it as a discussion here:
#923
But my conclusion is, that this is indeed an "issue".

My testing shows that this bit of code prevents NewUnitsEnabled to remain at 1.
scenario.cpp, line 2636:

#ifdef FIXIT_CSII //	checked - ajw 9/28/98 - Added runtime check.
    if (Is_Aftermath_Installed()) {
        if (Session.Type == GAME_SKIRMISH || Session.Type == GAME_GLYPHX_MULTIPLAYER) {
            bAftermathMultiplayer = NewUnitsEnabled = OverrideNewUnitsEnabled;
        }
    }
#endif

In globals.cpp there is this:
OverrideNewUnitsEnabled = false; // ST - 12/13/2019 12:21PM
and it seems only the remaster dllinterface.cpp has the code to make it become "true". While the non-remaster build has no such means. Non-remaster builds should not use "OverrideNewUnitsEnabled" there, in scenario.cpp.

[Gerwin2k]

Made a local VanillaRA build with this adjusted code (scenario.cpp, line 2636):

#ifdef FIXIT_CSII //	checked - ajw 9/28/98 - Added runtime check.
    if (Is_Aftermath_Installed()) {
        if (Session.Type == GAME_SKIRMISH || Session.Type == GAME_GLYPHX_MULTIPLAYER) {
#ifdef REMASTER_BUILD
			bAftermathMultiplayer = NewUnitsEnabled = OverrideNewUnitsEnabled;
#else
			bAftermathMultiplayer = NewUnitsEnabled; 
#endif
        }
    }
#endif

Now I can toggle the Skirmish game Aftermath-unit availability from within the "Aftrmath.ini" file:

[Aftermath]
NewUnitsEnabled=1