ocfs2: char is not always signed

Commit 1c66b360 (Change some lock status member in ocfs2_lock_res
to char.)  states that these fields need to be signed due to comparision
to -1, but only changed the type from unsigned char to char.   However, it
is a compiler option if char is a signed or unsigned type.  Change these
fields to signed char so the code will work with all compilers.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/ocfs2.h

@@ -159,9 +159,9 @@ struct ocfs2_lock_res {
 	char                     l_name[OCFS2_LOCK_ID_MAX_LEN];
 	unsigned int             l_ro_holders;
 	unsigned int             l_ex_holders;
-	char			 l_level;
-	char			 l_requested;
-	char			 l_blocking;
+	signed char		 l_level;
+	signed char		 l_requested;
+	signed char		 l_blocking;
 
 	/* Data packed - type enum ocfs2_lock_type */
 	unsigned char            l_type;