const runtime.gcDrainIdle

4 uses

	runtime (current package)
		mgc.go#L2003: 				gcDrain(&pp.gcw, gcDrainIdle|gcDrainUntilPreempt|gcDrainFlushBgCredit)
		mgcmark.go#L955: 	gcDrainIdle
		mgcmark.go#L989: 	idle := flags&gcDrainIdle != 0
		mgcmark.go#L997: 	if flags&(gcDrainIdle|gcDrainFractional) != 0 {