feature request

[Gene Raytsin]

I have notice that if you run "make package" for a port which depends on 
not yet installed
ports the actual package created only for this port, while all 
dependencies are simply installed without being
also created as packages.
It's not convinient when you have a task of redistributing several 
up-to-date ports along several systems.

I propose create another variable for the port build precedure, which 
will specify that package needs to be build.

In this case by using this variable in make.conf we can make sure that 
packages for all installed ports are build when needed.

To not to brake current idea of packaging _installed_ ports.  This 
variable needs to be processed by the "make install" procedure and not 
just make or make build.

Thanks,

Gene