const runtime.tlsSlots

3 uses

	runtime (current package)
		runtime2.go#L509: 	tlsSlots = 6
		runtime2.go#L510: 	tlsSize  = tlsSlots * goarch.PtrSize
		runtime2.go#L524: 	tls           [tlsSlots]uintptr // thread-local storage (for x86 extern register)