remove PDP-11 binaries, archives, tarballs

Remove the tarball of v7 UNIX (unpacked in ./v7)

Remove all PDP-11 binaries and constituent .a files
source package name is 'v7', version is '7.0'

Since the sources are *all* of V7 UNIX, rename the source package.
Use '7.0' as the version number, giving us a sub-digit to use for
upstream changes.

Set suite to 'unstable'.