Do not use prefixed clang for wasi

Rust 1.68 (rust-lang/rust#106489) broke this:

```
= note: clang-15: error: unsupported option '--export'
        clang-15: error: unsupported option '--stack-first'
        clang-15: error: unsupported option '--allow-undefined'
        clang-15: error: unsupported option '--fatal-warnings'
        clang-15: error: unsupported option '--no-demangle'
        clang-15: error: unsupported option '--gc-sections'
        clang-15: error: unknown argument: '-flavor'
        clang-15: error: no such file or directory: 'wasm'
        clang-15: error: no such file or directory: '__main_void'
```

Author: taiki-e

.github/workflows/ci.yml

@@ -50,17 +50,7 @@ jobs:
           - target: illumos
           - target: redox
           # - target: fuchsia
-          # TODO(wasi):
-          # = note: clang-15: error: unsupported option '--export'
-          #         clang-15: error: unsupported option '--stack-first'
-          #         clang-15: error: unsupported option '--allow-undefined'
-          #         clang-15: error: unsupported option '--fatal-warnings'
-          #         clang-15: error: unsupported option '--no-demangle'
-          #         clang-15: error: unsupported option '--gc-sections'
-          #         clang-15: error: unknown argument: '-flavor'
-          #         clang-15: error: no such file or directory: 'wasm'
-          #         clang-15: error: no such file or directory: '__main_void'
-          # - target: wasi
+          - target: wasi
           - target: emscripten
           - target: windows-gnu
           - target: windows-gnu

docker/wasi.Dockerfile

@@ -33,9 +33,10 @@ COPY --from=wasi-sdk /wasi-sdk "${TOOLCHAIN_DIR}"
 RUN --mount=type=bind,target=/docker \
     /docker/base/common.sh
 
-RUN --mount=type=bind,target=/docker \
-    COMMON_FLAGS="-L\"\${toolchain_dir}\"/lib -L\"\${toolchain_dir}\"/${RUST_TARGET}/lib/${RUST_TARGET}" \
-    /docker/clang-cross.sh
+# Do not use prefixed clang: https://github.com/taiki-e/setup-cross-toolchain-action/commit/fd352f3ffabd00daf2759ab4a3276729e52eeb10
+# RUN --mount=type=bind,target=/docker \
+#     COMMON_FLAGS="-L\"\${toolchain_dir}\"/lib -L\"\${toolchain_dir}\"/${RUST_TARGET}/lib/${RUST_TARGET}" \
+#     /docker/clang-cross.sh
 
 FROM ghcr.io/taiki-e/build-base:ubuntu-"${UBUNTU_VERSION}" as test-base
 SHELL ["/bin/bash", "-euxo", "pipefail", "-c"]