Fix a build error in MOBILE profile from accessibility impl code

Fix a build error in MOBILE profile from accessibility impl code

- There is no reason to have a different version for X11 vs Wayland, as
Paul mentioned in his patch (https://review.tizen.org/gerrit/#/c/54601/).
- But it's not true CURRENTLY, as EFL on Wayland has not been
implemented of full accessibility features.
- So on Wayland, we need to cut out some of features working on X11
including sending message to the indicator.
- That's what has been done by previous version of accessibility impl
files - accessibility-adaptor-impl-x.cpp & accessibility-adaptor-impl-wl.cpp.
- Currently no need to have ..-x.cpp & -wl.cpp again, because accessibility
features anyway should be implemented, and then we will only need one
impl file.
- Instead in this patch, #ifndef WAYLAND is used to decide whether current build configure is
for wayland or not. I believe this is acceptable for those difference
between X11 & Wayland supporting that would not be long-lasting.

Change-Id: Ia587261dbc343f5199a9fba7427bc30021b22979