Default to KHR extension

Fix #2530.
diff --git a/Test/baseResults/spv.bufferhandle7.frag.out b/Test/baseResults/spv.bufferhandle7.frag.out
index 3c8e86c..4282a36 100644
--- a/Test/baseResults/spv.bufferhandle7.frag.out
+++ b/Test/baseResults/spv.bufferhandle7.frag.out
@@ -5,7 +5,7 @@
 
                               Capability Shader
                               Capability PhysicalStorageBufferAddressesEXT
-                              Extension  "SPV_EXT_physical_storage_buffer"
+                              Extension  "SPV_KHR_physical_storage_buffer"
                               Extension  "SPV_KHR_storage_buffer_storage_class"
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel PhysicalStorageBuffer64EXT GLSL450