qcow, virtio-devices: Break cyclic dependency

Move the definition of RawFile from virtio-devices crate into qcow
crate. All the code that consumes RawFile also already depends on the
qcow crate for image file type detection so this change breaks the
need for the qcow crate to depend on the very large virtio-devices
crate.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

qcow/src/qcow.rs

@@ -6,26 +6,26 @@
 extern crate log;
 
 mod qcow_raw_file;
+mod raw_file;
 mod refcount;
 mod vec_cache;
 
+use crate::qcow_raw_file::QcowRawFile;
+use crate::refcount::RefCount;
+use crate::vec_cache::{CacheMap, Cacheable, VecCache};
 use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 use libc::{EINVAL, ENOSPC, ENOTSUP};
 use remain::sorted;
-use virtio_devices::RawFile;
+use std::cmp::{max, min};
+use std::fmt::{self, Display};
+use std::io::{self, Read, Seek, SeekFrom, Write};
+use std::mem::size_of;
 use vmm_sys_util::{
     file_traits::FileSetLen, file_traits::FileSync, seek_hole::SeekHole, write_zeroes::PunchHole,
     write_zeroes::WriteZeroes,
 };
 
-use std::cmp::{max, min};
-use std::fmt::{self, Display};
-use std::io::{self, Read, Seek, SeekFrom, Write};
-use std::mem::size_of;
-
-use crate::qcow_raw_file::QcowRawFile;
-use crate::refcount::RefCount;
-use crate::vec_cache::{CacheMap, Cacheable, VecCache};
+pub use crate::raw_file::RawFile;
 
 #[sorted]
 #[derive(Debug)]
@@ -367,8 +367,7 @@ fn max_refcount_clusters(refcount_order: u32, cluster_size: u32, num_clusters: u
 ///
 /// ```
 /// # use std::io::{Read, Seek, SeekFrom};
-/// # use virtio_devices::RawFile;
-/// # use qcow::{self, QcowFile};
+/// # use qcow::{self, QcowFile, RawFile};
 /// # fn test(file: std::fs::File) -> std::io::Result<()> {
 ///     let mut raw_img = RawFile::new(file, false);
 ///     let mut q = QcowFile::from(raw_img).expect("Can't open qcow file");
@@ -1703,7 +1702,6 @@ mod tests {
     use super::*;
     use std::io::{Read, Seek, SeekFrom, Write};
     use tempfile::tempfile;
-    use virtio_devices::RawFile;
 
     fn valid_header_v3() -> Vec<u8> {
         vec![