unix: add AT_REMOVEDIR, AT_EACCESS and AT_SYMLINK_FOLLOW on dragonfly

Change-Id: I2a3f4fb12ed3af1789af6115aecae62e61792549
Reviewed-on: https://go-review.googlesource.com/c/sys/+/326430
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/types_dragonfly.go

@@ -241,6 +241,9 @@ type Winsize C.struct_winsize
 const (
 	AT_FDCWD            = C.AT_FDCWD
 	AT_SYMLINK_NOFOLLOW = C.AT_SYMLINK_NOFOLLOW
+	AT_REMOVEDIR        = C.AT_REMOVEDIR
+	AT_EACCESS          = C.AT_EACCESS
+	AT_SYMLINK_FOLLOW   = C.AT_SYMLINK_FOLLOW
 )
 
 // poll

unix/ztypes_dragonfly_amd64.go

@@ -431,6 +431,9 @@ type Winsize struct {
 const (
 	AT_FDCWD            = 0xfffafdcd
 	AT_SYMLINK_NOFOLLOW = 0x1
+	AT_REMOVEDIR        = 0x2
+	AT_EACCESS          = 0x4
+	AT_SYMLINK_FOLLOW   = 0x8
 )
 
 type PollFd struct {