CI: Add emcc build to avoid any future regression

Author: ChinYikMing

.github/workflows/main.yml

@@ -58,13 +58,35 @@ jobs:
       uses: rlalik/setup-cpp-compiler@master
       with:
         compiler: ${{ matrix.compiler }}
+    - name: Setup emsdk
+      uses: mymindstorm/setup-emsdk@v14
+      with:
+        version: 3.1.51
+        actions-cache-folder: 'emsdk-cache'
     - name: fetch artifact first to reduce HTTP requests
       env:
         CC: ${{ steps.install_cc.outputs.cc }}
       run: |
             make artifact
             make ENABLE_SYSTEM=1 artifact
             make ENABLE_ARCH_TEST=1 artifact
+            # Hack Cloudflare 403 Forbidden on GitHub Runner for Doom artifact download
+            wget --header="User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:122.0) Gecko/20100101 Firefox/122.0" \
+                 --header="Referer: https://www.doomworld.com/" \
+                 --header="Accept-Language: en-US,en;q=0.9" \
+                 -O build/shareware_doom_iwad.zip \
+                 "https://www.doomworld.com/3ddownloads/ports/shareware_doom_iwad.zip"
+            unzip -d build/ build/shareware_doom_iwad.zip
+      if: ${{ always() }}
+    - name: default build using emcc
+      run: |
+            make CC=emcc -j$(nproc)
+      if: ${{ always() }}
+    - name: default build for system emulation using emcc
+      run: |
+            make distclean
+            make CC=emcc ENABLE_SYSTEM=1 -j$(nproc)
+            make distclean ENABLE_SYSTEM=1
       if: ${{ always() }}
     - name: default build with -g
       env: