const runtime.numSpanClasses

5 uses

	runtime (current package)
		mcache.go#L48: 	alloc [numSpanClasses]*mspan
		mcache.go#L57: 	reusableNoscan [numSpanClasses]gclinkptr
		mgcsweep.go#L59: 	numSweepClasses            = numSpanClasses * 2
		mheap.go#L211: 	central [numSpanClasses]struct {
		mheap.go#L585: 	numSpanClasses = gc.NumSizeClasses << 1