fix windows build

src/mmvec.rs

@@ -204,10 +204,11 @@ where
 
         // On Windows it is required that file is not mapped before resizing.
         // The safest option is to just drop and recreate the Data.
-        if cfg!(windows) {
+        #[cfg(windows)] {
             drop(self.data.take());
             self.data = Some(Data::from_file_unchecked_resized(self.path(), new_len)?);
-        } else {
+        }
+        #[cfg(not(windows))] {
             self.data.as_mut().map_or(Ok(()), |d| d.resize(new_len))?;
         }
 
@@ -417,9 +418,8 @@ fn resize_file_to_fit<T>(file: &File, header_size: u64, len: usize) -> io::Resul
 unsafe fn mmap(file: &File, offset: u64, len: usize) -> io::Result<MmapMut> {
     let mut opts = MmapOptions::new();
     let mmap = opts.offset(offset).len(len).map_mut(file)?;
-    if cfg!(unix) {
-        mmap.advise(memmap2::Advice::Random).ok();
-    }
+    #[cfg(unix)]
+    mmap.advise(memmap2::Advice::Random).ok();
     Ok(mmap)
 }