ci: cache the FFmpeg build of the macOS x86_64 target (#295)

The Intel macOS build and release actions are copies of the shared ones
that predate the FFmpeg cache, so every run rebuilt FFmpeg from scratch,
and under Rosetta at that. Give them the same cache step.

Author: devopvoid

.github/actions/build-macos-x86_64/action.yml

@@ -34,6 +34,17 @@ runs:
         key: webrtc-${{ env.WEBRTC_CACHE_BRANCH }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-jni/src/main/cpp/dependencies/webrtc/CMakeLists.txt') }}-${{ hashFiles('webrtc-jni/pom.xml') }}
         restore-keys: webrtc-${{ env.WEBRTC_CACHE_BRANCH }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-jni/src/main/cpp/dependencies/webrtc/CMakeLists.txt') }}-
 
+    - name: Derive the FFmpeg version from the pom
+      run: echo "FFMPEG_VERSION=$(sed -n 's|.*<ffmpeg.version>\([^<]*\)</ffmpeg.version>.*|\1|p' webrtc-java-media/pom.xml)" >> "$GITHUB_ENV"
+      shell: bash
+
+    - name: Set up FFmpeg cache
+      uses: actions/cache@v6
+      with:
+        path: ~/ffmpeg
+        key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
+        restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
+
     - name: Set up Maven cache
       uses: actions/cache@v6
       with:

.github/actions/release-macos-x86_64/action.yml

@@ -26,6 +26,17 @@ runs:
         key: webrtc-${{ env.WEBRTC_CACHE_BRANCH }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-jni/src/main/cpp/dependencies/webrtc/CMakeLists.txt') }}-${{ hashFiles('webrtc-jni/pom.xml') }}
         restore-keys: webrtc-${{ env.WEBRTC_CACHE_BRANCH }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-jni/src/main/cpp/dependencies/webrtc/CMakeLists.txt') }}-
 
+    - name: Derive the FFmpeg version from the pom
+      run: echo "FFMPEG_VERSION=$(sed -n 's|.*<ffmpeg.version>\([^<]*\)</ffmpeg.version>.*|\1|p' webrtc-java-media/pom.xml)" >> "$GITHUB_ENV"
+      shell: bash
+
+    - name: Set up FFmpeg cache
+      uses: actions/cache@v6
+      with:
+        path: ~/ffmpeg
+        key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
+        restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
+
     - name: Set up Maven cache
       uses: actions/cache@v6
       with: