The relevant namespace is exported and exposed to QML. Intended to help
tidy up the patch D25447 that shadows the enum values manually.
This doesn't compile for me:
[ 11%] Building CXX object src/engine/CMakeFiles/KF5BalooEngine.dir/indexerstate.cpp.o In file included from /home/nate/kde/src/baloo/src/engine/indexerstate.cpp:1: /home/nate/kde/src/baloo/src/engine/indexerstate.h:32:19: error: expected constructor, destructor, or type conversion before ‘(’ token 32 | Q_NAMESPACE_EXPORT(BALOO_ENGINE_EXPORT) | ^