Deprecate environment variables TARGET_CONFIGURE_ARGS and TARGET_CMAKE_ARGS

I'm a confused on what is going on with configure and CMake arguments, and as such it's impossible to save them in the database cleanly for all configurations. Here are my observations and suggestions to clean them up, at least for those that I understand.

• Cross-compilations don't have configure arguments, instead they set environment variables TARGET_CONFIGURE_ARGS and TARGET_CMAKE_ARGS.
  • Suggestion: keep the configure arguments as part of the coin configuration. If needed, an env var can be set by coin_agent, but I don't see why it would be needed.
  • All build workitems should have configure arguments
• Test workitems: are they supposed to have configure arguments or not? So far I see that some have but I don't understand the logic.

Expand for example this qtbase integration and see the column "configure arguments".