more efficient builds and support for staged builds

[Matthias Klose]

Building gtk+3.0, I see a few things which do matter for a bootstrap of the package on a new (slowish, because it's simulated) architecture.

Support for staged builds (DEB_STAGE=stage1 dpkg-buildpackage ...):

 - The package b-d's on colord and cups, creating a cyclic dependency. The
   staged build should configure without these b-d's and succeed.

 - The package builds udebs, doubling the build time. It would be nice
   if the package could be built without udebs (not sure if special cdbs
   support is needed, I only did remove the packages in the control file
   and references in the rules file.

Besides that

 - Please check if the package can be built in parallel, and support
   DEB_BUILD_OPTIONS="parallel=<N>"

- Please check if a binary-arch only build needs to build the documentation.

- Please check if the tests need to be built when building with
  DEB_BUILD_OPTIONS="nocheck". I see that a considerable amout
  of time is spent buildint the tests.

- Please document which b-d's are only needed to run the testsuite.

- Please check how to cross build the package.

It would be nice to address all of these, and then try to propose that package as an example how to build other packages in the gtk stack.

Thanks, Matthias