evas: make classes abstract

Summary:
those classes are defining pure_virtual functions, so the class should
be abstract.

ref T7632

Depends on D7670

Reviewers: cedric, segfaultxavi, zmike, q66

Reviewed By: segfaultxavi

Subscribers: #reviewers, #committers

Tags: #efl

Maniphest Tasks: T7632

Differential Revision: https://phab.enlightenment.org/D7671

src/lib/ector/software/ector_renderer_software.eo

@@ -1,4 +1,4 @@
-class Ector.Renderer.Software (Ector.Renderer)
+abstract Ector.Renderer.Software (Ector.Renderer)
 {
    [[Ector software renderer class]]
    data: null;

src/lib/evas/canvas/evas_canvas3d_object.eo

@@ -1,6 +1,6 @@
 import evas_canvas3d_types;
 
-class Evas.Canvas3D.Object (Efl.Object)
+abstract Evas.Canvas3D.Object (Efl.Object)
 {
    [[Evas 3D canvas object class]]
    data: Evas_Canvas3D_Object_Data;