In check shared-libs, use new internal tagging mechanism ->tag instead of the...

In check shared-libs, use new internal tagging mechanism ->tag instead of the global Lintian::Tag::tag.

Switches this check to a new tagging facility that will make it
possible to sort tags before they are issued. It will also eliminate
some error prone global variables surrounding profiles.

Please do not use the old global 'tag' facility from Lintian::Tag
in this check anymore.