runtime: implement string ops in Go
Also implement go:nosplit annotation. Not really needed
for now, but we'll definitely need it for other conversions.
benchmark old ns/op new ns/op delta
BenchmarkRuneIterate 534 474 -11.24%
BenchmarkRuneIterate2 535 470 -12.15%
LGTM=bradfitz
R=golang-codereviews, dave, bradfitz, minux
CC=golang-codereviews
https://golang.org/cl/93380044
diff --git a/src/pkg/runtime/race0.go b/src/pkg/runtime/race0.go
new file mode 100644
index 0000000..e9f72a4
--- /dev/null
+++ b/src/pkg/runtime/race0.go
@@ -0,0 +1,11 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !race
+
+// Dummy race detection API, used when not built with -race.
+
+package runtime
+
+const raceenabled = false
