* Add predefined version `D_Optimized` when compiling with `-O`
So that code can be aware of whether it's compiled with `-O`, e.g., to
distinguish between debug and optimized release builds (not necessarily
using `-release`).
* [update changelog/d_optimized.dd]
Co-authored-by: Petar Kirov <petar.p.kirov@gmail.com>
Co-authored-by: Petar Kirov <petar.p.kirov@gmail.com>
