elm_win: add new condition about engine set when generate the elm_win object

Summary:
Calling the elm_config_accel_preference_get api with "none" as parameter,
it means user does not want to use acceleration.

Reviewers: Hermet

Reviewed By: Hermet

Differential Revision: https://phab.enlightenment.org/D2920

legacy/elementary/src/lib/elm_config.h

@@ -919,6 +919,7 @@ EAPI const char *elm_config_accel_preference_get(void);
  * "gl", "opengl" - try use OpenGL.
  * "3d" - try and use a 3d acceleration unit.
  * "hw", "hardware", "accel" - try any acceleration unit (best possible)
+ * "none" - use no acceleration. try use software
  *
  * Since 1.14, it is also possible to specify some GL properties for the GL
  * window surface. This allows applications to use GLView with depth, stencil

legacy/elementary/src/lib/elm_win.c

@@ -3492,8 +3492,12 @@ _elm_win_finalize_internal(Eo *obj, Elm_Win_Data *sd, const char *name, Elm_Win_
              else
                {
 // add all engines with selected engine first - if any
-                  enginelist[p++] = ENGINE_GET();
-
+                  if (elm_config_preferred_engine_get())
+                    enginelist[p++] = elm_config_preferred_engine_get();
+// add check _elm_gl_preference whether "none" or not
+                  else if (!elm_config_accel_preference_get() ||
+                           strcmp(elm_config_accel_preference_get(),"none"))
+                    enginelist[p++] = elm_config_engine_get();
 // add all engines with gl/accelerated ones first - only engines compiled
 #ifdef HAVE_ELEMENTARY_X
                   enginelist[p++] = ELM_SOFTWARE_X11;