It seems that www.openh323.org no longer hosts the pwlib 1.2.20. The ebuild should be modified to point to a mirror (if there is one), or just be masked and wait for 1.3.x. Thanks
pwlib-1.2.20 is no longer available anywhere that I am aware of. pwlib-1.2.19 is the unmasked version currently. If your emerge is trying to download 1.2.20... do an "emerge --clean rsync" and it will then download the correct versions of pwlib and openh323.