[Issue 13025] Tools repository does not build on Ubuntu

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13025

--- Comment #12 from Martin Nowak <code at dawg.eu> ---
I think the following should work around the linker bug. Will try it when I'm
back home.

Mark __bss_start and _end as weak references, the linker is going to define
them anyhow, so no reference in main is necessary.

--