os: restore RemoveAll docs by making a single copy

Updates #29983

Change-Id: Ifdf8aa9c92e053374e301a4268d85e277c15f0b5
Reviewed-on: https://go-review.googlesource.com/c/160182
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/os/path.go

@@ -58,6 +58,14 @@ func MkdirAll(path string, perm FileMode) error {
 	return nil
 }
 
+// RemoveAll removes path and any children it contains.
+// It removes everything it can but returns the first error
+// it encounters. If the path does not exist, RemoveAll
+// returns nil (no error).
+func RemoveAll(path string) error {
+	return removeAll(path)
+}
+
 // endsWithDot reports whether the final component of path is ".".
 func endsWithDot(path string) bool {
 	if path == "." {

src/os/removeall_at.go

@@ -13,7 +13,7 @@ import (
 	"syscall"
 )
 
-func RemoveAll(path string) error {
+func removeAll(path string) error {
 	if path == "" {
 		// fail silently to retain compatibility with previous behavior
 		// of RemoveAll. See issue 28830.

src/os/removeall_noat.go

@@ -11,11 +11,7 @@ import (
 	"syscall"
 )
 
-// RemoveAll removes path and any children it contains.
-// It removes everything it can but returns the first error
-// it encounters. If the path does not exist, RemoveAll
-// returns nil (no error).
-func RemoveAll(path string) error {
+func removeAll(path string) error {
 	if path == "" {
 		// fail silently to retain compatibility with previous behavior
 		// of RemoveAll. See issue 28830.