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
Refactor to use ExternalProgram for the command instead of duplicating
that code (badly). Also improve messages to say "or not executable"
when a script/command is not found.
Also allow ExternalPrograms to be passed as arguments to
run_command(). The only thing we're doing by preventing that is
forcing people to use prog.path()
And actually test that prog.path() works. The earlier test was just
running the command without checking if it succeeded.
Also make everything use prog.get_command() or get_path() instead of
accessing the internal member prog.fullpath directly.
Jussi Pakkanen
Dylan Baker
Nirbheek Chauhan