don't count base repl buffer size as overhead

src/evict.cpp

@@ -380,7 +380,7 @@ size_t freeMemoryGetNotCountedMemory(void) {
 
     /* also don't count the replication backlog memory
      * that's where the replication clients get their memory from */
-    overhead += g_pserver->repl_backlog_size;
+    overhead += g_pserver->repl_backlog_size - g_pserver->repl_backlog_config_size;
 
     if (g_pserver->aof_state != AOF_OFF) {
         overhead += sdsalloc(g_pserver->aof_buf)+aofRewriteBufferSize();