unistd, test: Enable getpeereid on dragonfly

Author: woodruffw

src/unistd.rs

@@ -2795,6 +2795,7 @@ pub fn ttyname(fd: RawFd) -> Result<PathBuf> {
     target_os = "freebsd",
     target_os = "openbsd",
     target_os = "netbsd",
+    target_os = "dragonfly",
 ))]
 pub fn getpeereid(fd: RawFd) -> Result<(Uid, Gid)> {
     let mut uid = 1;

test/test_unistd.rs

@@ -1076,6 +1076,7 @@ fn test_getpeereid() {
     target_os = "freebsd",
     target_os = "openbsd",
     target_os = "netbsd",
+    target_os = "dragonfly",
 ))]
 fn test_getpeereid_invalid_fd() {
     // getpeereid is not POSIX, so error codes are inconsistent between different Unices.