CI: set up multi-thread build for all platforms

.github/workflows/macos.yml

@@ -26,7 +26,9 @@ jobs:
 
     - name: Build
       working-directory: ${{runner.workspace}}/build
-      run: cmake --build . --config ${{matrix.build_type}}
+      run: |
+        threads=`sysctl -n hw.logicalcpu`
+        cmake --build . --config ${{matrix.build_type}} --parallel $threads
 
     - name: Test
       working-directory: ${{runner.workspace}}/build