efl: general distcheck fixes

efl: general distcheck fixes

Summary:
- Added missing C++ header
- Added missing elementary header
- Removed generated header from elementary_SOURCES
  (Was added by raster in 42dfee37)
  Not sure of what would be the best place for it, though.
- Removed previously removed files from elementary examples Makefile.

Test Plan: Run 'make distcheck'

Reviewers: stefan, felipealmeida

Subscribers: cedric

Differential Revision: https://phab.enlightenment.org/D5800

Signed-off-by: Cedric Bail <cedric@osg.samsung.com>