reserve cl_mem_flags bits 21 and 22 for an upcoming Intel extension (#687)

Author: bashbaug

xml/cl.xml

@@ -793,7 +793,9 @@ server's OpenCL/api-docs repository.
         <enum bitpos="12"           name="CL_MEM_KERNEL_READ_AND_WRITE"/>
             <unused start="13" end="19"/>
         <enum bitpos="20"           name="CL_MEM_FORCE_HOST_MEMORY_INTEL"/>
-            <unused start="21" end="23"/>
+        <enum bitpos="21"           name="CL_MEM_RESERVED21_INTEL"/>
+        <enum bitpos="22"           name="CL_MEM_RESERVED22_INTEL"/>
+            <unused start="23" end="23"/>
         <enum bitpos="24"           name="CL_MEM_NO_ACCESS_INTEL"/>
         <enum bitpos="25"           name="CL_MEM_ACCESS_FLAGS_UNRESTRICTED_INTEL"/>
         <enum bitpos="26"           name="CL_MEM_USE_UNCACHED_CPU_MEMORY_IMG"/>