const golang.org/x/sys/unix.SYS_RT_SIGRETURN

one use

	golang.org/x/sys/unix (current package)
		zsysnum_linux_amd64.go#L25: 	SYS_RT_SIGRETURN            = 15

The pages are generated with Golds v0.4.9. (GOOS=linux GOARCH=amd64)