Fix references to rust-toolchain without .toml suffix

Two .gitignore files and a GitHub workflow referenced `rust-toolchain`
without a `.toml` extension, but all the files in the repo and the
generated files are `rust-toolchain.toml`.

In addition, have the GitHub workflow's hashing take
`*rust-toolchain.toml` into account, to allow for a future split between
the toolchain for compiling c2rust and the toolchain for compiling
c2rust-generated code that needs nightly.

Author: joshtriplett

.github/workflows/internal-testsuite.yml

@@ -39,7 +39,7 @@ jobs:
           ~/.rustup/toolchains
           ~/.rustup/update-hashes
           ~/.rustup/settings.toml
-        key: ${{ runner.os }}-rust-toolchain-${{ hashFiles('rust-toolchain') }}
+        key: ${{ runner.os }}-rust-toolchain-${{ hashFiles('**/*rust-toolchain.toml') }}
 
     - name: Cache Rust artifacts
       uses: actions/cache@v4

analysis/tests/.gitignore

@@ -1,5 +1,6 @@
 *.bc
-rust-toolchain
+# Sometimes generated by c2rust
+rust-toolchain.toml
 
 instrument.out.log
 instrument.err.jsonl

tests/.gitignore

@@ -19,7 +19,7 @@ c2rust-lib.rs
 !build.rs
 
 # sometimes generated by `c2rust`
-rust-toolchain
+rust-toolchain.toml
 
 # sometimes generated by `c2rust`, but only in `src/`
 **/src/Cargo.toml