Comment # 2 on bug 1023634 from Daniel Molkentin

I looked into it and it seems to work as intended: the systemd-bootchart module
will only be included if and only if systemd-bootchart is found. On
distributions that do not provide systemd-bootchart (which has been superseded
by systemd-analyze, an integral part of systemd), it's not required.

So this message is correct. Eventually the systemd-bootchart module will
probably be removed upstream, but until such time, you will see this (correct)
warning.