Kernel prepatch 4.15-rc6

The 4.15-rc6 kernel prepatch has beenreleased for testing. "This would have been a very quiet week, if itwasn't for the final x86 PTI stuff - and that shows in the diffstattoo. About half the rc6 work is x86 updates. The timing for this isn'twonderful, but it all looks nice and clean."