syscall: stub Getrlimit on wasip1

This is a prerequisite to enabling the pure Go resolver for
wasip1.

Change-Id: Iecd8a18ce4c9eb69a697d29930bedb7175b4f0ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/500577
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/syscall/syscall_wasip1.go

@@ -478,3 +478,16 @@ func SetNonblock(fd int, nonblocking bool) error {
 	errno := fd_fdstat_set_flags(int32(fd), flags)
 	return errnoErr(errno)
 }
+
+type Rlimit struct {
+	Cur uint64
+	Max uint64
+}
+
+const (
+	RLIMIT_NOFILE = iota
+)
+
+func Getrlimit(which int, lim *Rlimit) error {
+	return ENOSYS
+}