Cleanup: Fix build warning with MSVC

This cleans up the following warning

BLI_mempool.c(291):warning C4100: 'pool':unreferenced formal parameter

Warning introduced by c1d4b6f339

source/blender/blenlib/intern/BLI_mempool.c

@@ -290,7 +290,11 @@ static BLI_freenode *mempool_chunk_add(BLI_mempool *pool,
 
 static void mempool_chunk_free(BLI_mempool_chunk *mpchunk, BLI_mempool *pool)
 {
+#ifdef WITH_ASAN
   BLI_asan_unpoison(mpchunk, sizeof(BLI_mempool_chunk) + pool->esize * pool->csize);
+#else
+  UNUSED_VARS(pool);
+#endif
   MEM_freeN(mpchunk);
 }