Merge topic 'automoc-rerun-missing-dependency' into release-3.18

Source/cmQtAutoMocUic.cxx

Tests/QtAutogen/RerunMocOnMissingDependency/CMakeLists.txt

...issingDependency/MocOnMissingDependency/CMakeLists.txt.in

...nMocOnMissingDependency/MocOnMissingDependency/inc1/foo.h

...nMocOnMissingDependency/MocOnMissingDependency/inc2/foo.h

...runMocOnMissingDependency/MocOnMissingDependency/main.cpp

...ocOnMissingDependency/MocOnMissingDependency/myobject.cpp

...nMocOnMissingDependency/MocOnMissingDependency/myobject.h

Tests/QtAutogen/Tests.cmake