Duke3d: fix menu option to disable item pickup messages not saving to .cfg by adding "hud_messages" cvar

This bug appears to be rather old...

engine: fix "twitching" of models drawn with rotatesprite when the viewangle changes in polymost and polymer

engine: break glBufferData()/glBufferSubData() stuff out of polymost_drawpoly() and into polymost_startBufferedDrawing()/polymost_bufferVert()/polymost_finishBufferedDrawing() and use for polymost_printtext256() and polymer_drawartskyquad()

engine: set polymer sky according to the first sector drawn per frame instead of predetermining it at map load time

This allows maps that use more than one parallax sky texture to look more correct in polymer, assuming only one type of sky is visible at once.

voidwrap: add explicit "voidwrap" target to Makefile so I can "make voidwrap" and not "make voidwrap_steam_x64.dll", strip .dll after building, add UNREFERENCED_PARAMETER to DllMain() to silence warnings

It's nice that the Steam SDK was apparently updated to be compatible with MinGW at some point, so we aren't forced to build this .dll with MSVC anymore.

engine: work around GCC 12.1 issue with RELEASE=0 builds due to xxHash specifying forced inlining after inlining has been disabled via -O0/-Og

This should allow stuff like the upscale pack to work on devices where OpenGL isn't available at all.

Makefile: specify -frounding-math to make sure GCC and clang are on the same page regarding float behavior

This code is really weird. It's more than just the equivalent of offsetof().

engine: this condition should never happen, but mdgetskinmap() can return null and we weren't checking it

Makefile: remove -Wl,--allow-multiple-definition, -mwindows, -lmingw32, -lpthread, -pthread, -static-libgcc, -static-libstdc++, and add -Wl,-subsystem,windows

None of these seem to be needed anymore. Tested with MSYS2 and the newest MSVCRT based toolchain from https://winlibs.com

lld works with GCC builds too, but you have to disable LTO if you want to use it.

I left BeOS because it's still around as Haiku (haiku-os.org) and left Wii because devkitPro seems to be updated to at least gcc 11.2.0.

engine: skip CVAR_RESTARTVID handling for polymer-specific cvars when not running polymer, limit r_pr_shadowdetail to 5 (4096x4096)

Compiled with --disable-vp8-encoder --disable-vp9-encoder --enable-static-msvcrt --disable-avx --disable-multithread --disable-ssse3