This commit removes minor features of the test suite that I've never
seen used and that are basically just a maintenance burden:
- color_diagnostics: Diagnostics are colored by default when running
from a terminal, and not colored otherwise. This is the right behavior.
Being able to tweak this has minor value, and could be achieved by
modifying the %{compile_flags} instead if absolutely needed.
- ccache: This can be achieved by using a wrapper for the %{cxx}
substitution.
- _dump_macros_verbose is just a dead function now.
7e6221da10