Auto merge of #150722 - nikic:llvm-22, r=cuviper

Update to LLVM 22

Scheduled release date: Feb 24
1.94 becomes stable: Mar 5

Changes:
 * Update to rc2, with one patch to work around our outdated illumos sysroot (https://github.com/rust-lang/llvm-project/commit/41256ab128f2af613b4a16771cda6baa36b55f45).
 * Update the host toolchain as well, otherwise we lose cross-language LTO, in particular for jemalloc.
 * Adjust one loongarch assembly test. The split into r and s variants is based on the suggestion in https://github.com/rust-lang/rust/pull/151134.

Depends on:

 * [x] https://github.com/rust-lang/rust/pull/151410
 * [ ] https://github.com/rust-lang/rust/issues/150756
 * [x] https://github.com/llvm/llvm-project/issues/175190
 * [x] https://github.com/llvm/llvm-project/pull/175912
 * [x] https://github.com/llvm/llvm-project/issues/175965
 * [x] https://github.com/llvm/llvm-project/pull/176195
 * [x] https://github.com/llvm/llvm-project/issues/157073
 * [x] https://github.com/llvm/llvm-project/issues/176421
 * [x] https://github.com/llvm/llvm-project/pull/176925
 * [x] https://github.com/llvm/llvm-project/pull/177187