os, syscall: Hurd fixes for a couple of tests

Based on patch by Svante Signell.
    
    Reviewed-on: https://go-review.googlesource.com/c/161520

From-SVN: r268605

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-28b65174d9c9163f4ab2cfaf70dca646f1a7611f
+9b66264ed6adcf3fd215dbfd125c12b022b7280e
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/os/os_test.go

@@ -1336,6 +1336,10 @@ func TestSeek(t *testing.T) {
 			t.Logf("skipping test case #%d on nacl; https://golang.org/issue/21728", i)
 			continue
 		}
+		if runtime.GOOS == "hurd" && tt.out > 1<<32 {
+			t.Logf("skipping test case #%d on Hurd: file too large", i)
+			continue
+		}
 		off, err := f.Seek(tt.in, tt.whence)
 		if off != tt.out || err != nil {
 			if e, ok := err.(*PathError); ok && e.Err == syscall.EINVAL && tt.out > 1<<32 && runtime.GOOS == "linux" {

libgo/go/syscall/syscall_unix_test.go

@@ -46,11 +46,13 @@ func _() {
 	// fcntl file locking structure and constants
 	var (
 		_ = syscall.Flock_t{
-			Type:   int16(0),
-			Whence: int16(0),
-			Start:  int64(0),
-			Len:    int64(0),
-			Pid:    int32(0),
+			// Comment out the Type and Whence tests because
+			// on the Hurd they are int32, not int16.
+			// Type:   int16(0),
+			// Whence: int16(0),
+			Start: int64(0),
+			Len:   int64(0),
+			Pid:   int32(0),
 		}
 	)
 	const (