Link cl_khronos_vendor_id enums to OpenCL 3.0 in cl.xml (#737)

* Link `cl_khronos_vendor_id` to OpenCL 3.0 in cl.xml

See script to check for orphans in #730

* Attach assigned vendor IDs to OpenCL 1.0

This is so that they can clearly be used for any OpenCL version.

* Move the cl_khronos_vendor_id type back to OpenCL 3.0

This was the version that introduced the type.

xml/cl.xml

@@ -4466,6 +4466,14 @@ server's OpenCL/api-docs repository.
             <enum name="CL_SUBMITTED"/>
             <enum name="CL_QUEUED"/>
         </require>
+        <require comment="cl_khronos_vendor_id">
+            <!-- The cl_khronos_vendor_id type was added in OpenCL 3.0, but the
+                 concept of assigned vendor IDs has existed since OpenCL 1.0.
+                 These enums can be used in any OpenCL version because the type
+                 used in the API is cl_uint. -->
+            <enum name="CL_KHRONOS_VENDOR_ID_CODEPLAY"/>
+            <enum name="CL_KHRONOS_VENDOR_ID_POCL"/>
+        </require>
         <require comment="Platform APIs">
             <command name="clGetPlatformIDs"/>
             <command name="clGetPlatformInfo"/>