cl.xml Add values for cl_img_unified_svm_external_memory_dma_buf (KhronosGroup#1435)

* Add values for cl_img_unified_svm_external_memory_dma_buf extension

* Register cl_img_unified_svm_external_memory_dma_buf extension as experimental

Author: paulfradgley

xml/cl.xml

@@ -2295,7 +2295,9 @@ server's OpenCL/api-docs repository.
     </enums>
 
     <enums start="0x4220" end="0x422F" name="enums.4220" vendor="IMG">
-            <unused start="0x4220" end="0x422F"/>
+        <enum value="0x4220"        name="CL_SVM_ALLOC_EXTERNAL_MEMORY_DMA_BUF_VIRTUAL_ADDRESS_IMG"/>
+        <enum value="0x4221"        name="CL_SVM_ALLOC_EXTERNAL_MEMORY_DMA_BUF_IMG"/>
+            <unused start="0x4222" end="0x422F"/>
     </enums>
 
     <enums start="0x4230" end="0x423F" name="enums.4230" comment="Reserved for EXT extensions">
@@ -7719,5 +7721,14 @@ server's OpenCL/api-docs repository.
                 <enum name="CL_DEVICE_SPIRV_CAPABILITIES_KHR"/>
             </require>
         </extension>
+        <extension name="cl_img_unified_svm_external_memory_dma_buf" revision="1.1.0" supported="opencl" depends="cl_khr_unified_svm" experimental="true" comment="requires cl_khr_unified_svm 0.2.0 or later">
+            <require>
+                <type name="CL/cl.h"/>
+            </require>
+            <require comment="cl_svm_alloc_properties_khr">
+                <enum name="CL_SVM_ALLOC_EXTERNAL_MEMORY_DMA_BUF_VIRTUAL_ADDRESS_IMG"/>
+                <enum name="CL_SVM_ALLOC_EXTERNAL_MEMORY_DMA_BUF_IMG"/>
+            </require>
+        </extension>
     </extensions>
 </registry>