travis: Parallel build
travis: Parallel build

Use all available cores

Signed-off-by: Ola Jeppsson <793f970c52ded1276b9264c742f19d1888cbaf73@adapteva.com>

twocs/pal,mateunho/pal,RafaelRMA/pal,8l/pal,8l/pal,olajep/pal,Adamszk/pal3,parallella/pal,eliteraspberries/pal,parallella/pal,olajep/pal,debug-de-su-ka/pal,debug-de-su-ka/pal,eliteraspberries/pal,RafaelRMA/pal,RafaelRMA/pal,olajep/pal,aolofsson/pal,eliteraspberries/pal,parallella/pal,twocs/pal,Adamszk/pal3,parallella/pal,twocs/pal,mateunho/pal,parallella/pal,debug-de-su-ka/pal,debug-de-su-ka/pal,eliteraspberries/pal,aolofsson/pal,Adamszk/pal3,8l/pal,mateunho/pal,Adamszk/pal3,aolofsson/pal,mateunho/pal,twocs/pal,mateunho/pal,eliteraspberries/pal,8l/pal,RafaelRMA/pal,aolofsson/pal,debug-de-su-ka/pal,olajep/pal