[github-actions] macOS: Fix build with cython
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2abc38b..b83f408 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -29,7 +29,11 @@
       shell: bash
     - uses: actions/checkout@v2
     - name: autogen
-      run: ./autogen.sh
+      run: |
+          export PATH="$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin"
+          export LIBS="-L/Library/Frameworks/Python.framework/Versions/2.7/lib"
+          export PYTHON_EXTRA_LDFLAGS="-u _PyMac_Error /System/Library/Frameworks/Python.framework/Versions/2.7/Python"
+          ./autogen.sh
     - name: make
       run: make
     - name: make check