[vpr][pack] include required lib

Author: amin1377

vpr/src/pack/pack.cpp

@@ -18,6 +18,7 @@
 #include "vpr_context.h"
 #include "vpr_error.h"
 #include "vpr_types.h"
+#include "stats.h"
 #include "vtr_assert.h"
 #include "vtr_log.h"