Github Actions add MacOS build and fix Tools/setup/OSX.sh

- Tools/setup/OSX.sh wasn't installing px4-dev on fresh run

.github/workflows/compile_macos.yml

@@ -0,0 +1,61 @@
+name: MacOS build
+
+on:
+  push:
+    branches:
+    - 'master'
+  pull_request:
+    branches:
+    - '*'
+
+jobs:
+  build:
+    runs-on: macos-10.15
+    strategy:
+      matrix:
+        config: [
+          px4_fmu-v5_default,
+          tests, # includes px4_sitl
+          ]
+    steps:
+    - uses: actions/checkout@v1
+      with:
+        token: ${{secrets.ACCESS_TOKEN}}
+
+    - uses: actions/cache@v2
+      with:
+        path: ~/Library/Caches/pip
+        key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-
+
+    - name: setup
+      run: ./Tools/setup/OSX.sh
+
+    - name: Prepare ccache timestamp
+      id: ccache_cache_timestamp
+      shell: cmake -P {0}
+      run: |
+        string(TIMESTAMP current_date "%Y-%m-%d-%H;%M;%S" UTC)
+        message("::set-output name=timestamp::${current_date}")
+    - name: ccache cache files
+      uses: actions/cache@v2
+      with:
+        path: ~/.ccache
+        key: ${{matrix.config}}-ccache-${{steps.ccache_cache_timestamp.outputs.timestamp}}
+        restore-keys: ${{matrix.config}}-ccache-
+    - name: setup ccache
+      run: |
+          mkdir -p ~/.ccache
+          echo "base_dir = ${GITHUB_WORKSPACE}" > ~/.ccache/ccache.conf
+          echo "compression = true" >> ~/.ccache/ccache.conf
+          echo "compression_level = 6" >> ~/.ccache/ccache.conf
+          echo "max_size = 400M" >> ~/.ccache/ccache.conf
+          ccache -s
+          ccache -z
+
+    - name: make ${{matrix.config}}
+      run: |
+          ccache -z
+          make ${{matrix.config}}
+          ccache -s