fixup! ci: drop Circle CI in favor of Github Actions

.github/workflows/build_matrix.yml

@@ -194,8 +194,16 @@ jobs:
         if: contains('failure success', steps.build.conclusion) && !cancelled()
         run: |
           set -x
-          # Trim the build directory.
+          # Trim the build directory, but keep the staging luajit
+          # headers (necessary for generating the Android APK).
+          if [[ '${{ matrix.target }}' == 'android' ]]; then
+            mv build/staging/include/luajit-2.1 .
+          fi
           rm -rf build/{cmake,staging,thirdparty}
+          if [[ '${{ matrix.target }}' == 'android' ]]; then
+            mkdir -p build/staging/include
+            mv luajit-2.1 build/staging/include/
+          fi
           ccache --cleanup >/dev/null
           ccache --show-stats --verbose