Use vec! in oid! macro

Signed-off-by: Klim Tsoutsman <klimusha@gmail.com>

src/lib.rs

@@ -282,12 +282,7 @@ impl<'a> PartialEq<OID> for &'a OID {
 #[macro_export]
 macro_rules! oid {
     ( $( $e: expr ),* ) => {{
-        let mut res = Vec::new();
+        $crate::OID::new(vec![$($crate::BigUint::from($e as u64)),*])
-
-        $(
-            res.push($crate::BigUint::from($e as u64));
-        )*
-        $crate::OID::new(res)
     }};
 }