Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

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

@@ -0,0 +1,13 @@
+// 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", note = "Use `__errno_location()` instead")]
+    pub fn __error() -> *mut ::c_int {
+        &mut errno
+    }
+}
+
+extern "C" {
+    #[thread_local]
+    pub static mut errno: ::c_int;
+}