Update the wasi toolchain.

Update the WASI build to LLVM 14.0 and the wasi-libc version from wasi-sdk-15.

This will require a ci-mirrors.rust-lang.org file load. Specifically, we
need [this LLVM release tarball] uploaded to be downloadable from
[this URL].

[this LLVM release tarball]: https://github.com/llvm/llvm-project/releases/download/llvmorg-14.0.0/clang+llvm-14.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz
[this URL]: https://ci-mirrors.rust-lang.org/rustc/2022-05-10-clang%2Bllvm-14.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz

Author: sunfishcode

src/ci/docker/host-x86_64/dist-various-2/build-wasi-toolchain.sh

@@ -2,15 +2,15 @@
 
 set -ex
 
-# Originally from https://github.com/llvm/llvm-project/releases/download/llvmorg-11.0.0/clang+llvm-11.0.0-x86_64-linux-gnu-ubuntu-16.04.tar.xz
-curl https://ci-mirrors.rust-lang.org/rustc/2021-01-14-clang%2Bllvm-11.0.1-x86_64-linux-gnu-ubuntu-16.04.tar.xz | \
+# Originally from https://github.com/llvm/llvm-project/releases/download/llvmorg-14.0.0/clang+llvm-14.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz
+curl https://ci-mirrors.rust-lang.org/rustc/2022-05-10-clang%2Bllvm-14.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz | \
   tar xJf -
-export PATH=`pwd`/clang+llvm-11.0.1-x86_64-linux-gnu-ubuntu-16.04/bin:$PATH
+export PATH=`pwd`/clang+llvm-14.0.0-x86_64-linux-gnu-ubuntu-18.04/bin:$PATH
 
 git clone https://github.com/WebAssembly/wasi-libc
 
 cd wasi-libc
-git reset --hard ad5133410f66b93a2381db5b542aad5e0964db96
+git reset --hard 9886d3d6200fcc3726329966860fc058707406cd
 make -j$(nproc) INSTALL_DIR=/wasm32-wasi install
 
 cd ..