fix doxygen test on Travis

it seems that doxygen 1.18.13 is not behaving the same as 1.1811 (Travis one).
one might need to remove some spaces in the signature as they are different depending on Doxygen's version

Author: 3nids

.ci/travis/code_layout/install.sh

@@ -16,7 +16,8 @@
 export CORES=2
 
 mkdir build
-cd build
+pushd build
 
 cmake -DWITH_CORE=OFF -DWITH_APIDOC=ON -DWITH_ASTYLE=ON -DENABLE_TESTS=ON ..
-make -j${CORES}
+
+popd

.ci/travis/code_layout/script.sh

@@ -15,6 +15,10 @@
 set -e
 
 pushd build
+
 export CTEST_BUILD_COMMAND="/usr/bin/make -j3 -i -k"
-python ${TRAVIS_BUILD_DIR}/.ci/travis/scripts/ctest2travis.py xvfb-run ctest -V --output-on-failure -S ${TRAVIS_BUILD_DIR}/.ci/travis/travis.ctest
+python3 ${TRAVIS_BUILD_DIR}/.ci/travis/scripts/ctest2travis.py xvfb-run ctest -V --output-on-failure -S ${TRAVIS_BUILD_DIR}/.ci/travis/travis.ctest
+
+ctest -V -R PyQgsDocCoverage
+
 popd