Build time over travis time limit again

[Andrey Mokhov]

Joachim, Ben,

I gave it a try on my machine. 

First of all, we currently need "--flavour=quick" instead of "quickest" because the latter builds only vanilla RTS.

If I do:

./build.bat -j --flavour=quick
./build.bat -j --flavour=quick validate

Then the testsuite completes, but I get a lot of errors, particularly in "ghci/", "perf/" and "th/". Most of them can probably be fixed relatively easily in Hadrian, but this requires a good understanding of which GHC features these tests actually depend on. I'll create an issue in the Hadrian repo to track down these testsuite failures and will CC you.

Cheers,
Andrey