stub out more types/funcs to compile against golang.org/x/net/internal/socket (#4037)

* stub out more types/funcs to compile against golang.org/x/net/internal/socket

These are changes need to compile github.com/domainr/dnsr/ with TinyGo.
See issue https://github.com/tinygo-org/net/issues/14.

These change are mostly to fix missing symbols in src/crypto/tls and
src/net.  Missing types and functions are cut-and-pasted from go1.21.4.
Functions are stubbed out returning errors.New("not implemented").

DNRS is compiled by running tinygo test:

   sfeldma@nuc:~/work/dnsr$ tinygo test -target=wasi

With this patch, and a corresponding patch for tinygo-org/net to fixup
src/net, you should get a clean compile.

src/syscall/syscall.go

@@ -1,3 +1,28 @@
 package syscall
 
+import (
+	"errors"
+	"sync/atomic"
+)
+
+const (
+	MSG_DONTWAIT = 0x40
+	AF_INET      = 0x2
+	AF_INET6     = 0xa
+)
+
 func Exit(code int)
+
+type Rlimit struct {
+	Cur uint64
+	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")
+}