`f128` on wasm does not support maximum intrinsic

[ChrisDenton]

The maximum intrinsic seems to be missing for wasm. See #150075 (comment)

unexpected runtime library name: fmaximum_numl
UNREACHABLE executed at /checkout/src/llvm-project/llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp:952!

[tgross35]

Easy repro with --target wasm32-unknown-unknown https://rust.godbolt.org/z/Mxnhnxqoq:

#![feature(f128)]

#[unsafe(no_mangle)]
pub fn f128_max(a: f128, b: f128) -> f128 {
    a.max(b)
}

We actually don't need a quick fix on the Rust side for that PR, just a gate update. This would build but not run correctly on almost all platforms anyway because of llvm/llvm-project#44744.

[tgross35]

llvm/llvm-project#207100