Added define for new reflection probe API update (case 1290521)

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -251,6 +251,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Default black texture XR is now opaque (alpha = 1).
 - Changed ray tracing acceleration structure build, so that only meshes with HDRP materials are included (case 1322365).
 - Changed default sidedness to double, when a mesh with a mix of single and double-sided materials is added to the ray tracing acceleration structure (case 1323451).
+- Use the new API for updating Reflection Probe state (fixes garbage allocation, case 1290521)
 
 ## [11.0.0] - 2020-10-21
 

com.unity.render-pipelines.high-definition/Runtime/Unity.RenderPipelines.HighDefinition.Runtime.asmdef

@@ -28,6 +28,11 @@
             "name": "com.unity.modules.xr",
             "expression": "1.0.0",
             "define": "ENABLE_XR_MODULE"
+        },
+        {
+            "name": "Unity",
+            "expression": "2021.2.0a16",
+            "define": "REFLECTION_PROBE_UPDATE_CACHED_DATA_AVAILABLE"
         }
     ],
     "noEngineReferences": false