Placeholder commit to clarify history

Prior to this commit, the 'wheezy' branch was one commit on top of
the tag debian/krb5-1.10.1+dfsg-6, but neither that code nor that version
actually appeared in wheezy.  Instead, an NMU by the security team was
made to wheezy-security containing the patch in question (an upstream
security fix).

After this commit, the wheezy branch has the tree as of the tag
debian/krb5-1.10.1+dfsg-5, which is the last version that was in wheezy
by way of unstable.  The previous state of the wheezy branch is recorded
as a second parent, to avoid rewriting history in the public repository.
The security team's NMU can now be added to this packaging repo, and
further development performed on top of it.