debian: add support for multiarch

Enhance the debian build rules so it will create multiarch compliant
packages on those distributions that have support for it.

Also remove e2initrd-helper from the e2fsprogs package since no one
uses it any more.

Also update the debian policy standards version to 3.9.2.

Addresses-Debian-Bug: #632169

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
24 files changed