Fix div_ceil with rand and serde too

Author: cuviper

src/bigrand.rs

@@ -66,7 +66,7 @@ impl<R: Rng + ?Sized> RandBigInt for R {
         let len = (digits + (rem > 0) as u64)
             .to_usize()
             .expect("capacity overflow");
-        let native_digits = bit_size.div_ceil(&64);
+        let native_digits = Integer::div_ceil(&bit_size, &64);
         let native_len = native_digits.to_usize().expect("capacity overflow");
         let mut data = vec![0u64; native_len];
         unsafe {

src/biguint/serde.rs

@@ -89,7 +89,7 @@ impl<'de> Visitor<'de> for U32Visitor {
         use num_integer::Integer;
 
         let u32_len = seq.size_hint().unwrap_or(0);
-        let len = u32_len.div_ceil(&2);
+        let len = Integer::div_ceil(&u32_len, &2);
         let mut data = Vec::with_capacity(len);
 
         while let Some(lo) = seq.next_element::<u32>()? {