Don't error if the oppportunistic statat fails in fd_count

It was reported that old kernels (2.6) will return a failure if
SYMLINK_NOFOLLOW is used, so lets check for errors here.

Author: eminence

src/process/mod.rs

@@ -1181,12 +1181,13 @@ impl Process {
     /// Calling this function is more efficient than calling `fd().unwrap().count()`
     pub fn fd_count(&self) -> ProcResult<usize> {
         // Use fast path if available (Linux v6.2): https://github.com/torvalds/linux/commit/f1f1f2569901
-        let stat = wrap_io_error!(
+        if let Ok(stat) = wrap_io_error!(
             self.root.join("fd"),
             rustix::fs::statat(&self.fd, "fd", AtFlags::SYMLINK_NOFOLLOW)
-        )?;
-        if stat.st_size > 0 {
-            return Ok(stat.st_size as usize);
+        ) {
+            if stat.st_size > 0 {
+                return Ok(stat.st_size as usize);
+            }
         }
 
         let fds = wrap_io_error!(