Let's do the iOS specific stuff in separate main() source
file(s). Don't attempt to build complete iOS programs using normal
LibreOffice mechanisms, it will work for only the very lowest level
unit tests anyway, because of static linking and the circularish
UNO/URE/bootstrap/whatnot (run-time) dependencies between different
parts of the code.

We thus can't build the various iOS-specific *_cppunittester_all unit
test executables any more. Corresponding unit tests (and more complex
ones) for iOS will have to be done in a different way.