runtime/race: tell race detector what memory Read/Write syscalls touch
Fixes #5567.

R=golang-dev, dave, iant
CC=golang-dev
https://golang.org/cl/10085043
diff --git a/src/pkg/runtime/race.go b/src/pkg/runtime/race.go
index 1d64ba3..2a9124d 100644
--- a/src/pkg/runtime/race.go
+++ b/src/pkg/runtime/race.go
@@ -24,6 +24,8 @@
 
 func RaceRead(addr unsafe.Pointer)
 func RaceWrite(addr unsafe.Pointer)
+func RaceReadRange(addr unsafe.Pointer, len int)
+func RaceWriteRange(addr unsafe.Pointer, len int)
 
 func RaceSemacquire(s *uint32)
 func RaceSemrelease(s *uint32)