Show warnings about unreadable files even with verbosity == 0

I had a semi-corrupt encfs (which I detected, thanks to this tool!). A
file was only partially readable. Somewhere in the middle, an IOError
occured. Essentially, this is a corrupt file system -- which this tool
is meant to help detect --, so this class of errors shouldn't be
suppressed by "-q".

src/bitrot.py

@@ -221,13 +221,12 @@ class Bitrot(object):
             try:
                 new_sha1 = sha1(p, self.chunk_size)
             except (IOError, OSError) as e:
-                if self.verbosity:
-                    print(
-                        '\rwarning: cannot compute hash of {} [{}]'.format(
-                            p, errno.errorcode[e.args[0]],
-                        ),
-                        file=sys.stderr,
-                    )
+                print(
+                    '\rwarning: cannot compute hash of {} [{}]'.format(
+                        p, errno.errorcode[e.args[0]],
+                    ),
+                    file=sys.stderr,
+                )
                 continue
 
             cur.execute('SELECT mtime, hash, timestamp FROM bitrot WHERE '