extensions/arm/cl_arm_printf.txt

The cl_arm_printf 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/arm/cl_arm_printf.html

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

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