evas gl: make 9 patch work

evas gl: make 9 patch work

Summary:
The 9 patch is using image_stretch_region_get, but GL did not override it.
So the 9 patch did not work for GL engine at all.

Test Plan:
Evas_Object*img = evas_object_image_filled_add(evas);
evas_object_image_file_set(img, "test.9.png", 0);
evas_object_show(img);

Reviewers: Hermet, jsuya, herb, cedric

Reviewed By: Hermet

Subscribers: #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D12192

Change-Id: I3e455a9d0b89a82c3cf2f16683454d2e7c120e43