[1.8>1.9] [MERGE #4684 @MikeHolman] fix assert in JIT data serialization

Merge pull request #4684 from MikeHolman:serializedassert

We may have multiple codegen calls for same entrypoint, so replace the old JIT data if this happens

OS: 15845157

lib/Runtime/Base/FunctionBody.h

@@ -437,7 +437,12 @@ namespace Js
     public:
         void SetSerializedRpcData(const unsigned char* data, size_t size)
         {
-            Assert(serializedRpcData == nullptr);
+            if (this->serializedRpcData != nullptr)
+            {
+                // We may have multiple codegens happen for same entrypoint
+                const unsigned char* rpcData = this->serializedRpcData;
+                HeapDeleteArray(this->serializedRpcDataSize, rpcData);
+            }
             serializedRpcData = data;
             serializedRpcDataSize = size;
         }