unix: fix build on DragonFly BSD

The code was broken such that it didn't compile. With this fix, it compiles.

Fixes golang/go#20055.

Change-Id: I9aeb4900f2c99b2ad254be75b4987913cae71e14
Reviewed-on: https://go-review.googlesource.com/41672
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/syscall_dragonfly.go

@@ -57,7 +57,7 @@ func nametomib(name string) (mib []_C_int, err error) {
 }
 
 func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
 }
 
 func direntReclen(buf []byte) (uint64, bool) {
@@ -65,7 +65,7 @@ func direntReclen(buf []byte) (uint64, bool) {
 	if !ok {
 		return 0, false
 	}
-	return (16 + namlen + 1 + 7) & ^7, true
+	return (16 + namlen + 1 + 7) &^ 7, true
 }
 
 func direntNamlen(buf []byte) (uint64, bool) {