Syncs with the config of the current `main` branch (as used for 4.2+)
as far as possible (backports the last couple of years of PRs, minus
the removal of some platforms and of the Mono builds).
Notably backports #128 and #131, giving us these toolchains:
- Base image: Fedora 39
- Mono version: 6.12.0.198
- SCons: 4.5.2
- Linux: GCC 13.2.0 built against glibc 2.28, binutils 2.40, from our own [Linux SDK](https://github.com/godotengine/buildroot)
- Windows: MinGW 11.0.0, GCC 13.2.1, binutils 2.40
- HTML5: Emscripten 3.1.39 (standard builds), Emscripten 1.39.9 (Mono builds)
- Android: Android NDK 23.2.8568313, build-tools 33.0.2, platform android-33, CMake 3.22.1, JDK 11
- macOS: Xcode 15.0 with Apple Clang (LLVM 16.0.0), MacOSX SDK 14.0
- iOS: Xcode 15.0 with Apple Clang (LLVM 16.0.0), iPhoneOS SDK 17.0
- UWP: Unchanged, current Dockerfile still unsupported
We now provide pre-built toolchains for Linux with old glibc and the required
Godot dependencies, which can be used to build portable Godot binaries without
having to be on an extremely old Linux distro.
So we can retire the old Ubuntu 14.04 containers and instead do our portable
builds directly on Fedora 34, like for other platforms.
This commit also makes use of `godot-mono-builds` to build Mono and the BCL
for Linux, instead of doing it manually. The same will be done for Windows and
macOS in the next commit.
