detect packages which are built against missing libraries

[Jona Joachim]

Hi!
The last upgrade of devel/icu broke a lot of binaries for me
because they were missing libicui18n.so.36.
I quickly hacked together a python script which tries to
indentify which packages were built against no longer existing
libraries.
It outputs a list of packages which can easily be combinded with
portupgrade -f.
It depends on portupgrade.
I just post it here in case it can be useful for anybody.
It is a good idea to run pkgdb -F before running it.

-- 
:wq Jona