enable ci on non-main branches

.github/workflows/build-branch.yml

@@ -0,0 +1,97 @@
+name: Build working branch
+
+on:
+  push:
+    branches:
+      - '!main'
+
+jobs:
+
+  build-linux:
+    runs-on: ubuntu-18.04
+    strategy:
+      matrix:
+        platform: [gcc]
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Setup Ninja
+        uses: ashutoshvarma/setup-ninja@master
+        with:
+          version: 1.10.2
+      - name: Build
+        env:
+          CC: ${{ steps.vars.outputs.cc }}
+          CXX: ${{ steps.vars.outputs.cxx }}
+          MATRIX_PLATFORM: ${{ matrix.platform }}
+        run: .github/scripts/build-linux.sh
+      - name: Test
+        run: |
+          cd build
+          ctest --verbose
+      - name: Upload artifact
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: actions/upload-artifact@v1
+        with:
+          name: artifacts
+          path: linux-amd64.tar.gz
+
+  build-macos:
+    runs-on: macos-10.15
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Setup Ninja
+        uses: ashutoshvarma/setup-ninja@master
+        with:
+          version: 1.10.2
+      - name: Build
+        run: |
+          .github/scripts/build-macos.sh
+      - name: Test
+        run: |
+          cd build
+          ctest --verbose
+      - name: Upload artifact
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: actions/upload-artifact@v1
+        with:
+          name: artifacts
+          path: darwin-amd64.tar.gz
+
+  build-windows:
+    runs-on: windows-2019
+    strategy:
+      matrix:
+        platform: [x86, amd64]
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Setup Ninja
+        uses: ashutoshvarma/setup-ninja@master
+        with:
+          version: 1.10.2
+      - uses: ilammy/msvc-dev-cmd@v1.4.1
+        with:
+          arch: ${{ matrix.platform }}
+      - name: Build
+        run: |
+          .github/scripts/build-msvc.ps1
+        env:
+          MATRIX_PLATFORM: ${{ matrix.platform }}
+      - name: Test
+        run: |
+          cd build
+          ctest --verbose -C RelWithDebInfo
+      - name: Upload artifact
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: actions/upload-artifact@v1
+        with:
+          name: artifacts
+          path: windows-${{ matrix.platform }}.zip