As we are trying to reach parity between opencl-c.h and
-fdeclare-opencl-builtins, ensure the documentation mentions that new
builtins should be added to both.
Reviewed by: Anastasia Stulova
**Library functionality**
If an extension adds functionality that does not modify standard language
-parsing it should not require modifying anything other than header files or
+parsing it should not require modifying anything other than header files and
``OpenCLBuiltins.td`` detailed in :ref:`OpenCL builtins <opencl_builtins>`.
Most commonly such extensions add functionality via libraries (by adding
non-native types or functions) parsed regularly. Similar to other languages this