[dynarmic, docs] Add support for DragonFly, shared mapping fallback to private, and update docs (#2829)

Add deps instructions for void linux, alpine, nixOS, DragonFlyBSD, update haiku new stuff; add basic coding guidelines

Also fixes ucontext on dragonfly :)

Allows fallback if ftruncate() fails (DragonFly doesnt like shm of big files with hammer2...) This will also indirectly help OpenIndiana and Solaris since they dont like big shared files either.

The downside is that no inspection of the memory can be easily done. But that's just an edge case anyways.

Signed-off-by: lizzie <lizzie@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2829
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

docs/Caveats.md

@@ -1,5 +1,16 @@
 # Caveats
 
+<!-- TOC -->
+- [Arch Linux](#arch-linux)
+- [Gentoo Linux](#gentoo-linux)
+- [macOS](#macos)
+- [Solaris](#solaris)
+- [HaikuOS](#haikuos)
+- [OpenBSD](#openbsd)
+- [FreeBSD](#freebsd)
+- [NetBSD](#netbsd)
+<!-- /TOC -->
+
 ## Arch Linux
 
 - httplib AUR package is broken. Set `httplib_FORCE_BUNDLED=ON` if you have it installed.
@@ -53,6 +64,8 @@ For this reason this patch is NOT applied to default on all platforms (for obvio
 
 `cubeb_devel` will also not work, either disable cubeb or uninstall it.
 
+Still will not run flawlessly until `mesa-24` is available. Modify CMakeCache.txt with the `.so` of libGL and libGLESv2 by doing the incredibly difficult task of copy pasting them (`cp /boot/system/lib/libGL.so .`)
+
 ## OpenBSD
 
 After configuration, you may need to modify `externals/ffmpeg/CMakeFiles/ffmpeg-build/build.make` to use `-j$(nproc)` instead of just `-j`.