To avoid duplicate typedef with the definition in glext.h
V2: test for both GL_OES_EGL_image and GL_EXT_EGL_image_storage in
case both the GL and GLES headers are included. Per Emil.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107488
Tested-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Mathias Fröhlich <mathias.froehlich@web.de>