gl: remove invalid read and write

gl: remove invalid read and write

Summary:
There could be 2 evas_gl_image referencing 1 evas_gl_texture.
evas_object_image_orient_set could make this case.
In this case, when one evas_gl_image is removed(free), the evas_gl_texture
is not removed because its reference count.
After this point, if the other evas_gl_image is removed without drawing
(see function evas_gl_common_image_draw, line "im->tex->im = im")
then evas_gl_texture is reading invalid adress when it is removed.

Reviewers: Hermet, jsuya, herb, devilhorns

Reviewed By: devilhorns

Subscribers: devilhorns, cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D12229

Change-Id: I6e7dc894ab314a45ddaadeba709ea2b35360b43a