Fix int_in_range using more bytes than necessary

`offset` counts the number of bytes but the range is shifted as if it
counted the number of bits. This causes int_in_range to consume more
bytes than necessary.

The `int_in_range::<u32>(0..=u8::MAX)` case from the new test fails
without this commit.

src/unstructured.rs

@@ -322,7 +322,7 @@ impl<'a> Unstructured<'a> {
         let mut offset: usize = 0;
 
         while offset < mem::size_of::<T>()
-            && (range >> T::Widest::from_usize(offset)) > T::Widest::ZERO
+            && (range >> T::Widest::from_usize(offset * 8)) > T::Widest::ZERO
         {
             let byte = bytes.next().ok_or(Error::NotEnoughData)?;
             result = (result << 8) | T::Widest::from_u8(byte);
@@ -701,4 +701,16 @@ mod tests {
         let choice = *u.choose(&[42]).unwrap();
         assert_eq!(choice, 42)
     }
+
+    #[test]
+    fn int_in_range_uses_minimal_amount_of_bytes() {
+        let mut u = Unstructured::new(&[1]);
+        u.int_in_range::<u8>(0..=u8::MAX).unwrap();
+
+        let mut u = Unstructured::new(&[1]);
+        u.int_in_range::<u32>(0..=u8::MAX as u32).unwrap();
+
+        let mut u = Unstructured::new(&[1]);
+        u.int_in_range::<u32>(0..=u8::MAX as u32 + 1).unwrap_err();
+    }
 }