Merge pull request #23 in CASA/casaviewer from CAS-13536 to release/1.1
* commit '44d2a53c000479eb678b56e5710275fc08c9652e':
Trigger a build
seems like build for casaviewer/6.2.1 may have switched to manylinux (CAS-13536)
the casacore Mutex.cc disappearance again (CAS-13536)
pick up casa6 changes (CAS-13536)