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
Remove the code responsible for implicitly compressing manpages as .gz
files. It has been established that manpage compression is a distro
packager's task, with existing distros already having their own
implementations of compression.
Fixes#4330