Add support for building packages for multiple architecture

[scaronni]

Packages that can exist in both format (i686/x86_64) in the same repository cannot be built together.

Examples:

• a proprietary library "oracle" would need oracle-libs.i686 and oracle-libs.x86_64 be both available as in the normal repositories.
• the 32 bit Flash plugin is required on x86_64 by Steam for showing videos in the Store pages.

[leamas]

Both these examples extends lpf beyond it's current design goal to only handle leaf packages. To be honest, I have deferred this out of sheer laziness. Because depending on a lpf package is, by definition to depend on a manual procedure - whatever a lpf packages provides it's not there until it's built.

The flash plugin looks simple enough to work for me. Probably, steam should install and start whether it's there or not (?), having some kind of fallback if it's not there. Isn't this just a question of adding the lpf-flash-plugin package?

OTOH, the oracle case looks like something which really depends on oracle-libs. Since the creation of these libs can't be automated if they are lpf stuff, how is this supposed to work "scratching my head".

[leamas]

Flash plugin lpf package review request submitted. Closing this bug, as the rest refers to a non-leaf package which raises issuesmentioned above.