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
Solaris doesn't ship static libraries, so the test can't rely on libz.a
existing on Solaris.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>