runtime, internal/syscall/unix: mark getrandom vDSO as non-escaping

Updates #66779
Updates #69577

Change-Id: I0dea5a30aab87aaa443e7e6646c1d07aa865ac1c
GitHub-Last-Rev: 1cea46deb3
GitHub-Pull-Request: golang/go#69719
Reviewed-on: https://go-review.googlesource.com/c/go/+/616696
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>

src/internal/syscall/unix/getrandom.go

@@ -13,6 +13,7 @@ import (
 )
 
 //go:linkname vgetrandom runtime.vgetrandom
+//go:noescape
 func vgetrandom(p []byte, flags uint32) (ret int, supported bool)
 
 var getrandomUnsupported atomic.Bool

src/runtime/vgetrandom_linux.go

@@ -11,6 +11,7 @@ import (
 	"unsafe"
 )
 
+//go:noescape
 func vgetrandom1(buf *byte, length uintptr, flags uint32, state uintptr, stateSize uintptr) int
 
 var vgetrandomAlloc struct {