Exclude unsupported builds from travis
Exclude unsupported builds from travis

The libasync driver is not yet ready to be built on these compilers, and I don't intend to work it out until a little later.

This will allow the vibe.d repo to go green again soon
mfrischknecht/vibe.d,redstar/vibe.d,fast4shoot/vibe.d,yannick/vibe.d,sigod/vibe.d,nathanchristenson/vibe.d,Geod24/vibe.d,etcimon/vibe.0,ColdenCullen/vibe.d,sigod/vibe.d,AndreyMZ/vibe.d,alphaKAI/vibe.d,veelo/vibe.d,sigod/vibe.d,nathanchristenson/vibe.d,Kozzi11/vibe.d,alphaKAI/vibe.d,etcimon/vibe.d,Mihail-K/vibe.d,etcimon/vibe.0,Yoplitein/vibe.d,nathanchristenson/vibe.d,gedaiu/vibe.d,alphaKAI/vibe.d,schuetzm/vibe.d,DBankov/vibe.d,Yoplitein/vibe.d,etcimon/vibe.d,Yoplitein/vibe.d,machindertechnologies/vibe.d,rejectedsoftware/vibe.d,chalucha/vibe.d