syscall: remove some dead code

Not sure why it's here but it's not referenced anywhere.

src/syscall/syscall.go

@@ -2,7 +2,6 @@ package syscall
 
 import (
 	"errors"
-	"sync/atomic"
 )
 
 const (
@@ -18,11 +17,6 @@ type Rlimit struct {
 	Max uint64
 }
 
-// origRlimitNofile, if not {0, 0}, is the original soft RLIMIT_NOFILE.
-// When we can assume that we are bootstrapping with Go 1.19,
-// this can be atomic.Pointer[Rlimit].
-var origRlimitNofile atomic.Value // of Rlimit
-
 func Setrlimit(resource int, rlim *Rlimit) error {
 	return errors.New("Setrlimit not implemented")
 }