Quit running foreign unittests >_<

[Nick Sabalausky via Digitalmars-d]

This is getting to be (or rather, *continuing* to be) a royal PITA:

https://github.com/rejectedsoftware/vibe.d/issues/673

I don't mean to pick on Vibe.d in particular, but can we have a solution 
(that doesn't involve obscure corners of druntime, or demanding everyone 
use the same build system) for running our unittests *without* 
triggering a cascading avalanche of unittests from ALL third party libs 
that don't cooperate with the [frankly] quite clumsy 
version(mylib_unittests) hack?!