This reverts commit a599eeab78, plus follow-up
fa4431449d "Avoid bogus loplugin:dllmacro
'unnecessary *DLLPUBLIC declaration ...'". See (abandoned)
<https://gerrit.libreoffice.org/#/c/42983/> "loplugin:dllmacro: Handle implicit
member functions" how this would have needed to be extended to give consistent
results across Linux and macOS, but then would have started to remove DLLPUBLIC
from entities that apparently need to at least have default type visibility on
macOS and started to make tests fail.
on classes which are fully defined in a header file
Rename the dllprivate plugin to dllmacro and add the functionality
there.
Change-Id: I4581d551c46a8f61213d95973f323359d08278d8
