Allows getting closer to `./run_project_tests.py -- -Dwerror=true`.
- when argc and argv are not *both* used, there's a standard, compliant
mechanism to mark the variable as unused
- generated code should not build as -Werror
- more thoroughly comment out some commented code
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082