Respect GOMAXPROCS variable
Respect GOMAXPROCS variable

Closes #535

restic/restic,ar-jan/restic,fawick/restic,arithmetric/restic,jayme-github/restic,ckemper67/restic,fawick/restic,restic/restic,middelink/restic,middelink/restic,stuertz/restic,stuertz/restic,byo/restic,ar-jan/restic,kurin/restic,byo/restic,jayme-github/restic,kurin/restic