chore: Upgrade RTS Dependencies

[luc-blaeser]

Upgrading Motoko RTS dependencies:

• LLVM 18.1.8
• Rust 1.82.0

Special aspects:

• Support for both wasm32 and wasm64.
• Support new dylink.0 instead of dylink.
• Support GOT.mem for RTS in the Motoko linker.
• LLVM LLD (used for wasm-ld) needs a bug fix: [lld][WebAssembly] Fix relocation of Wasm table index with GOT access llvm/llvm-project#104043. Therefore, patching wasm-ld.
• Float formatting is now based on Rust and no longer on musl. There are format changes to output of NaN and infinity. Moreover, one particular output format (hexadecimal float) is no longer supported. Updating the documentation and base library is needed.
• musl is still used in 32-bit but not in 64-bit. In the future, we should get rid of musl entirely. The musl import is rather old, upgrading is complicated as it involves a lot of unwanted dependencies.
• No longer using emscripten for 64-bit Wasm compilation (as there is a nix build issue with latest emscripten). Instead, the clang compiler is directly invoked.
• Adjusting the RTS code in line with the latest Rust features/rules.
• The new Rust core library bloats the RTS binary size (especially due to print formatter logic). Therefore, wasm-opt is applied to again reduce it to an acceptable size.

Note:

• If your nix-shell crashes with a segmentation fault with this PR, you need to upgrade nix. For this, you need to manually uninstall and re-install nix.

[github-actions]

Comparing from 247aa05 to a6d1305:
In terms of gas, 4 tests regressed, 1 tests improved and the mean change is -0.0%.
In terms of size, 5 tests regressed and the mean change is +29.3%.

[crusso]

Could it be that the change from 02 to 0z is causing the rts size increase?

[luc-blaeser]

I believe the increase would be even higher with O2. I'll double check and let you know.