Issue with Z-Buffer for GL4ES

[SteffenHaeuser]

On AmigaOS4 GL4ES compile light effects look "through" walls and doors.

This can be fixed if in Engine/Graphics/DrawPort.cpp the line

#ifdef arm

is changed into

#if defined(arm)||defined(amigaos4)

Probably better would be to change it to check for GL4ES with some define (not sure if such a define exists). Currently I compile with the line

#if defined(arm)||defined(amigaos4), if compiling for GL4ES on AmigaOS4, and with

#ifdef arm if compiling for MiniGL (AmigaOS4 machines either have MiniGL, a OpenGL 1.x variant, or GL4ES, depending on which graphics board is used, the newer ones support both APIs, the old ones only MiniGL).

Note for some reasion github does not show the _ _ which is present at "arm" and "amigaos4" in the front and behind.

[ptitSeb]

I think adding the amigaos ifdef in SeriousEngine source is the best way. It can be tricky to guess the opengl driver in run time, not sure it's worth the pain.