Bug#500198: apt headers should not pollute user namespaces with "using".

[Daniel Burrows <dburrows@debian.org>]

Package: apt
Version: 0.7.14+b1
Severity: minor

  A lot of the apt headers have "using" statements.  This is generally
considered poor C++ programming practice and should be fixed.  I
suggest we address this when there's an ABI and/or API break (as
some users of the library might be accidentally relying on apt pulling
names into scope).

  Daniel