fix gcc:4.8.5 can not get cores.

.github/workflows/build-gcc.yml

@@ -33,6 +33,7 @@ jobs:
       options: >-
         -v /usr/local:/host_usr_local
         -v "${{ github.workspace }}":/workspace
+        --workdir /workspace
 
     steps:
       - uses: actions/checkout@v1
@@ -41,6 +42,7 @@ jobs:
 
       - uses: friendlyanon/fetch-core-count@v1
         id: cores
+        if: matrix.gcc_version != '4.8.5'
 
       - name: Set output
         id: strings

.github/workflows/build.yml

@@ -74,20 +74,20 @@ jobs:
         # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
         # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
         run: >
-          cmake -B ${{ steps.strings.outputs.build-output-dir }}
+          cmake -B "${{ steps.strings.outputs.build-output-dir }}"
           -DCMAKE_CXX_COMPILER=${{ matrix.cpp_compiler }}
           -DCMAKE_C_COMPILER=${{ matrix.c_compiler }}
           -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-          -S ${{ github.workspace }}
+          -S "${{ github.workspace }}"
 
       - name: Build
         # Build your program with the given configuration. Note that --config is needed because the default Windows generator is a multi-config generator (Visual Studio generator).
         run: >-
-          cmake --build ${{ steps.strings.outputs.build-output-dir }}
+          cmake --build "${{ steps.strings.outputs.build-output-dir }}"
           --config ${{ matrix.build_type }}
 
       - name: Test
-        working-directory: ${{ steps.strings.outputs.build-output-dir }}
+        working-directory: "${{ steps.strings.outputs.build-output-dir }}"
         # Execute tests defined by the CMake configuration. Note that --build-config is needed because the default Windows generator is a multi-config generator (Visual Studio generator).
         # See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
         run: ctest --output-on-failure --build-config ${{ matrix.build_type }}