[MacPorts] #52606: atlas: add gcc6 variant.

[MacPorts]

#52606: atlas: add gcc6 variant.
--------------------------+----------------------
  Reporter:  Schamschula  |      Owner:  Veence
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:  haspatch
      Port:  atlas        |
--------------------------+----------------------

Comment (by Veence):

 Atlas needs a complete overhaul. The 3.10.3 version is out.

 But the major problem is this: ‘atlas’ requires the CPU to run at full
 speed to properly measure performance. But MacOS 10.11+ apparently won’t
 let it do that: it automatically inserts idle cycles to keep the CPU cool
 when it detects the temperature rises too fast. That will thwart any
 attempt to derive meaningful measures.

 I'll have first to figure out a way to de-activate that behaviour. I think
 I’ve stumbled on something trawling through the Internet, but it’ll take a
 bit of time to figure out how to piece everything together.

--
Ticket URL: <https://trac.macports.org/ticket/52606#comment:2>
MacPorts <https://www.macports.org/>
Ports system for OS X