Mark efl_types.eot as stable

Mark efl_types.eot as stable

Summary:
This allows using Efl_Version without EFL_BETA_API_SUPPORT, which in turn
allows failing when trying to use restricted BETA API with a more meaningful
error message.
The error will now tell you which restricted API you are trying to use, instead
of Efl_Version symbol not found.

Fixes T7696
Depends on D7932

Test Plan:
make && make check && make examples continue working.
Building a BETA example while removing the EFL_BETA_API_SUPPORT define should
tell you which BETA API you tried to use.

Reviewers: zmike, bu5hm4n, cedric

Subscribers: #reviewers, #committers

Tags: #efl

Maniphest Tasks: T7696

Differential Revision: https://phab.enlightenment.org/D7948