Reserve enum block for Google extensions. (#918)

Signed-off-by: Jeremy Kemp <jeremy@jeremykemp.co.uk>

Author: Jeremy-Kemp

xml/cl.xml

@@ -2260,8 +2260,12 @@ server's OpenCL/api-docs repository.
             <unused start="0x4280" end="0x428F"/>
     </enums>
 
-    <enums start="0x4290" end="0x4FFF" name="enums.4290" comment="Reserved for vendor extensions. Allocate in groups of 16.">
-            <unused start="0x4290" end="0x4FFF"/>
+    <enums start="0x4290" end="0x429F" name="enums.4290" vendor="Google">
+            <unused start="0x4290" end="0x429F"/>
+    </enums>
+
+    <enums start="0x42A0" end="0x4FFF" name="enums.42A0" comment="Reserved for vendor extensions. Allocate in groups of 16.">
+            <unused start="0x42A0" end="0x4FFF"/>
     </enums>
 
     <enums start="0x10000" end="0x10FFF" name="enums.10000" vendor="Khronos" comment="Experimental range for internal development only. Do not allocate.">