evas: fix distcheck build of ector evas engine
In commit fbe92aa67f18f8c0401cdc6d4440ed512c43b131 a dependency on the
software_generic header file was brought to the gl_generic module.
The include path to make this work was updated for meson but not for the
TravisCI distcheck builds found this for us.
Reviewed-by: Hermet Park <email@example.com>
Differential Revision: https://phab.enlightenment.org/D7468