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
When a static library link_whole to a bunch of other static libraries,
we have to extract all their objects recursively. But that could
introduce duplicated objects. ar is dumb enough to allow this without
error, but once the resulting static library is linked into an
executable or shared library, the linker will complain about duplicated
symbols.