experiment: build RTS outside of Nix environment

.github/workflows/rts-outside-nix.yml

@@ -0,0 +1,22 @@
+# Build RTS outside of Nix environment
+
+name: RTS
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+
+jobs:
+  build-outside-nix:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: Swatinem/rust-cache@v2
+    - name: Download dependencies
+      run: |
+        sudo apt install -y llvm musl clang-13
+        git clone https://github.com/WebAssembly/wasi-libc ../wasi-libc && cd ../wasi-libc && git checkout c5264e2bbe532994d06b039005f2af91bedcc1a6
+        git clone --branch v1.2.0 --depth 1 https://github.com/libtom/libtommath ../libtommath
+    - name: Build RTS
+      run: make -C rts

rts/rust-toolchain.toml

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+[toolchain]
+channel = "nightly-2023-04-21"
+components = [ "rust-src" ]
+targets = ["wasm32-unknown-emscripten"]