cmake: Add option for "mem: per-CPU allocator cache (ThunderX2 workaround)"

Change-Id: I7156cf433b2081246d1d9b8e4fde489609676ef1

kernel/cls.c

@@ -42,7 +42,9 @@ void cpu_local_var_init(void)
 		clv[i].monitor = monitor->cpu + i;
 		clv[i].rusage = rusage.cpu + i;
 		INIT_LIST_HEAD(&clv[i].smp_func_req_list);
+#ifdef ENABLE_PER_CPU_ALLOC_CACHE
 		clv[i].free_chunks.rb_node = NULL;
+#endif
 	}
 
 	cpu_local_var_initialized = 1;