extensions/img/cl_img_use_gralloc_ptr.txt

The cl_img_use_gralloc_ptr.txt extension is no longer authored in plain text.

Please refer to the HTML extension specification instead,
which may be found here:

https://www.khronos.org/registry/OpenCL/extensions/img/cl_img_use_gralloc_ptr.html

The asciidoc source for this extension specification may
be found here:

https://github.com/KhronosGroup/OpenCL-Docs/blob/master/extensions/cl_img_use_gralloc_ptr.asciidoc