Generate subpkg manifests by rule

One of the most tedious parts of using rpm is generating
%files manifests for subpkgs accurately.

The work is quite tedious because the files to be packaged force
a rebuild each time (unless --short-circuit is used or abused) to
test whether the patterns used to specify %files manifests
are correct.

There's a great deal of room for error, and its all manual labor.

Meanwhile, the packaging rules are pretty well understood these
days for all distros, and could be automated with rules.

Not all packages will conform to whatever rules are devised. But
lots of package %files manifests are utterly predictable with some very
simple rules, and other packages could be handled with a "opt-out"
disabler, or vice versa, where rule based packaging could be "opt-in".

Tobias Gerschner (formerly of Yoper Linux, now combined with Unity Linux)
had interest in pursuing rule based subpkg manifests originally.