kstrto*: accept "-0" for signed conversion

strtol(3) et al accept "-0", so should we.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index ec8da78..94be244 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -152,7 +152,7 @@
 		rv = _kstrtoull(s + 1, base, &tmp);
 		if (rv < 0)
 			return rv;
-		if ((long long)(-tmp) >= 0)
+		if ((long long)-tmp > 0)
 			return -ERANGE;
 		*res = -tmp;
 	} else {