evas: clean up GL images for emojis when GL context is free'd in shutdown process

evas: clean up GL images for emojis when GL context is free'd in shutdown process

If GL context is free'd before processing font shutdown,
textures for emoji glyph's GL images will be free'd without clean up its GL images.
It causes eina mempool infinite loop issue when emoji's GL images are free'd
in shutdown process.
So, the patch will make a list for emoji's GL images in context and clean up them
when the context is free'd. Just like font textures in context.

@tizen_fix

Change-Id: I3904f9aff74888e227a4f2143c4ff607ebb82415
(cherry picked from commit cecaf12a3bea725b53041126031c58035d76dfd1)