Add a sanity check of the doc generation stage in gitlab pages release ci job...

Add a sanity check of the doc generation stage in gitlab pages release ci job to avoid a respawn of the bug fixed by 08d2a0a6.

.gitlab-ci.yml

@@ -375,6 +375,9 @@ pages:
         - 'cmake -DBUILD_WRAPPER_PYTHON=ON -DBUILD_WRAPPER_MATLAB=ON -DBUILD_DOCUMENTATION=ON -DCMAKE_INSTALL_PREFIX=/opt/local/faust -DCPACK_PACKAGE_FILE_NAME=faust-$CI_COMMIT_TAG -DCPACK_PACKAGE_VERSION=$CI_COMMIT_TAG -DEXCLUDE_FAUST_LIB_INSTALL=ON  -DINCLUDE_ALL_SYS_INSTALL_INSTRUCS=ON ..'
         - make doc
         - make doc_exclu_class_filtering
+          # test that the doc generation works well (at least that html files for the pyfaust and matfaust namespaces exist)
+          # in order to avoid publishing an empty API doc
+        - if [ ! -r doc/html/namespacepyfaust.html -o ! -r doc/html/namespacematfaust.html ]; then echo "error with doxygen doc generation" 2>&1 && exit 1; fi
         - mkdir -p ../public/last-doc
         - cp -Rf doc/html ../public/last-doc/
         - mkdir -p ../public/packages