Made sure an error code is issued for failed mounts

In case of failure to mount a file system, an error code is expected to
indicate the failure reason. In an unclear case the error code was not
set, so force an EIO when this happens.

src/lowntfs-3g.c

@@ -4368,9 +4368,12 @@ static int ntfs_open(const char *device)
 	}
         
 	errno = 0;
+	goto out;
 err_out:
+	if (!errno)	/* Make sure to return an error */
+		errno = EIO;
+out :
 	return ntfs_volume_error(errno);
-        
 }
 
 static void usage(void)

src/ntfs-3g.c

@@ -4076,9 +4076,12 @@ static int ntfs_open(const char *device)
 	}
 	
 	errno = 0;
+	goto out;
 err_out:
+	if (!errno)
+		errno = EIO;
+out :
 	return ntfs_volume_error(errno);
-	
 }
 
 static void usage(void)