Move several dependencies to Build-Depends-Indep <!nodoc>

• d/control: Only require graphviz for Architecture: all builds

  This reduces the length of dependency chains for bootstrapping or re-bootstrapping architectures, for example during the 64-bit time_t transition.

• d/control, d/rules: Only run rdfind and symlinks if we built documentation

• d/control: Don't build -dev-doc package under nodoc build-profile

  This allows the -l10n package to be built without also needing to build developer documentation.

Closes: #1067455

The second and third commits are optional, the first is the highest-impact.