ganesha-rados-grace: use int type for getopt retval

the implicit conversion of a -1 retval from getopt is interpreted as a
value of 255 on an aarch64 platform, which then causes the default case
of the switch statement to always print a usage message and exit.

Signed-off-by: Michael Fritch <mfritch@suse.com>
Change-Id: I21caf0c4882d3c9b821836c000c1645287b9ba5c

src/tools/ganesha-rados-grace.c

@@ -108,7 +108,7 @@ int main(int argc, char * const *argv)
 	char			*pool = DEFAULT_RADOS_GRACE_POOL;
 	char			*oid = DEFAULT_RADOS_GRACE_OID;
 	char			*ns = NULL;
-	char			c;
+	int			c;
 	const char * const	*nodeids;
 	bool			do_add;