broken import gcstats in dmd-v2.023

[sa]

the file is in dmd-v2.023/src/druntime/src/gc/basic/gcstats.d
and declared: module gc.gcstats;

However, if I do:
import gc.gcstats;

dmd says: module gcstats cannot read file 'gc/gcstats.d'

if I do:

import gcstats;

dmd says: module gcstats cannot read file 'gcstats.d'

So how do I import gcstats?