emscripten CI: Use standard setup-emsdk way to cache

.github/workflows/emscripten.yml

@@ -2,7 +2,8 @@ name: Emscripten Build
 on: [push, pull_request]
 
 env:
-  emscripten-version: 2.0.25
+  EM_VERSION: 2.0.25
+  EM_CACHE_FOLDER: 'emsdk-cache'
 
 jobs:
   build:
@@ -13,24 +14,21 @@ jobs:
       with:
         submodules: true
 
-    - name: Cache .emscripten_cache
+    - name: Setup cache
+      id: cache-system-libraries
       uses: actions/cache@v2
       with:
-        path: emscripten-cache
-        key: emscripten-cache-${{ env.emscripten-version }}
+        path: ${{env.EM_CACHE_FOLDER}}
+        key: ${{env.EM_VERSION}}-${{ runner.os }}
 
     - name: Setup Emscripten toolchain
       uses: mymindstorm/setup-emsdk@v10
       with:
-        version: ${{ env.emscripten-version }}
-        actions-cache-folder: emsdk-cache
+        version: ${{ env.EM_VERSION }}
+        actions-cache-folder: ${{env.EM_CACHE_FOLDER}}
 
     - name: Build
-      env:
-        EM_CACHE: ${{ github.workspace }}/emscripten-cache/cache
-        EM_PORTS: ${{ github.workspace }}/emscripten-cache/ports
       run: |
-        mkdir -p emscripten-cache
         mkdir -p out/wasm
         cd out/wasm
         emcmake cmake -DCMAKE_BUILD_TYPE=MinSizeRel ../../src/