Merge pull request #1875 from cmusser/master

src/unix/bsd/freebsdlike/dragonfly/errno.rs

 // DragonFlyBSD's __error function is declared with "static inline", so it must
 // be implemented in the libc crate, as a pointer to a static thread_local.
 f! {
+    #[deprecated(since = "0.2.77", "Use `__errno_location()` instead")]
     pub fn __error() -> *mut ::c_int {
         &mut errno
     }

src/unix/bsd/freebsdlike/dragonfly/mod.rs

@@ -1044,6 +1044,7 @@ f! {
 }
 
 extern "C" {
+    pub fn __errno_location() -> *mut ::c_int;
     pub fn setgrent();
     pub fn mprotect(
         addr: *mut ::c_void,