Eo do: simplify eo_do macro.

Eo do: simplify eo_do macro.

This moves the mainloop check inside the function. There was never need
for it to be in client code (i.e a header/macro).
This is better suited inside eo_do_start because this is a macro some
bindings have to re-implement, and we definitely don't want it to be any
more complicated than it has to be.

This breaks ABI and makes elm 1.12 depend on efl 1.11. This is not an issue
as because of eolian and interfaces it's already the case.