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
It is sometimes important to be able to build projects offline, in that
case subproject tarballs and patches could be shipped directly within
the project's repository.
subproject using wrap-file is broken since commit (68bd64c Prevent
projects from directly grabbing files from other subprojects. )
subproject with wrap-file usually have version number after name
- **sproj_name** is `zlib-1.2.8` according to `directory = zlib-1.2.8`
of zlib.wrap
- but **self.subproject** `zlib`