Auto merge of rust-lang#22046 - mneumann:dragonfly-libstd-fixes, r=huonw

Author: bors

src/libstd/sys/unix/c.rs

@@ -72,7 +72,8 @@ pub const WNOHANG: libc::c_int = 1;
 #[cfg(target_os = "linux")]
 pub const _SC_GETPW_R_SIZE_MAX: libc::c_int = 70;
 #[cfg(any(target_os = "macos",
-          target_os = "freebsd"))]
+          target_os = "freebsd",
+          target_os = "dragonfly"))]
 pub const _SC_GETPW_R_SIZE_MAX: libc::c_int = 71;
 #[cfg(target_os = "openbsd")]
 pub const _SC_GETPW_R_SIZE_MAX: libc::c_int = 101;
@@ -94,6 +95,7 @@ pub struct passwd {
 #[repr(C)]
 #[cfg(any(target_os = "macos",
           target_os = "freebsd",
+          target_os = "dragonfly",
           target_os = "openbsd"))]
 pub struct passwd {
     pub pw_name: *mut libc::c_char,