locktest: remove manual declaration of errno

locktest.c has already #included <errno.h>, so remove the unneeded
(and in some cases, incorrect) manual declaration of errno as an
integer.  Some C libraries use a macro to provide thread-safety for
errno, so it's incorrect to try to provide a manual declaration.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

src/locktest.c

@@ -779,7 +779,6 @@ main(int argc, char *argv[])
     char	*p;
     extern char	*optarg;
     extern int	optind;
-    extern int	errno;
     int fail_count = 0;; 
     
     atexit(cleanup);