const runtime.traceBlockUntilGCEnds

3 uses

	runtime (current package)
		mgc.go#L573: 		goparkunlock(&work.sweepWaiters.lock, waitReasonWaitForGCCycle, traceBlockUntilGCEnds, 1)
		traceruntime.go#L103: 	traceBlockUntilGCEnds
		traceruntime.go#L123: 	traceBlockUntilGCEnds:        "wait until GC ends",