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
Former test is extremely hard to follow,
target names are inconsistent with directory names,
test case mixes up 2 separate testing scenarios,
names are meaningless. In order to fix this
provides comments what each command is doing and why,
renamed targets into descriptive and longer names,
made names consistent with contents so that it is easier
to follow test logic without looking up source code.
Currently sources, generated sources, or objects are considered to be
sources for a target, but link_whole should also fulfill the sources
requirement.
Fixes#2180