Merge topic 'aix-streams'

817db64c fix compile error on AIX/gcc-2.9 because of unknown std::stringstream
Merge topic 'FindGTK2-X11'

55f5ea7b FindGTK2: search for Fontconfig and X11 before using them
Merge topic 'sphinx-python3'

d55671ad Utilities/Sphinx: Fix cmake domain document removal with python3
Merge branch 'master' into next
Merge branch 'sphinx-python3' into release
Merge branch 'release'
Merge branch 'master' into next