Remove HW_buffer_counter after irrlichmt fix to remove HWBufferMap

[paradust7]

Fixes issue #12231, in conjunction with minetest/irrlicht#99 (comment)

[sfan5]

This is exactly the kind of fix I had in mind, thanks for looking at this.

For now the old code should not be removed but put inside #if IRRLICHT_VERSION_MT_REVISION < 5 so people can still build with older IrrlichtMt temporarily.

[lhofhansl]

Cool... Happy to see my old hack removed!

[lhofhansl]

Wait. We merged this before the Irrlicht change. Let's either revert this or merge the Irrlicht change quickly.
(I didn't have a chance to test it, yet).

[lhofhansl]

@SmallJoker @sfan5

[sfan5]

I assume that was an oversight, I'll merge the Irrlicht PR since it's fine anyway.
Though I wonder whether most people remember to pull irrlichtmt updates too or whether they'll accidentally end up running a Minetest with this change and Irrlicht without the other one.

[SmallJoker]

I do not update IrrlichtMt often so that recent Minetest builds continue to work (and do not need LD_PRELOAD with an old IrrlichtMt build). That makes bisecting and compatibility testing much easier. So yes indeed, people might indeed not update IrrlichtMt in sync with Minetest.

[sfan5]

It's okay if people use irrlichtmt tagged at a revision, the compatibility #if's can deal with this. What might cause problems is random git commits.