more -Wall warning fixes from Cristian Ionescu-Idbohrn.
This time it resulted in small code changes:

function                                             old     new   delta
nexpr                                                820     828      +8
tail_main                                           1200    1202      +2
wrapf                                                166     167      +1
parse_mount_options                                  227     209     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/1 up/down: 11/-18)             Total: -7 bytes

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 4fff20d..14aa593 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -120,8 +120,11 @@
 
 				/* If not this device, skip rest of line */
 				/* (regexec returns whole pattern as "range" 0) */
-				if (result || off[0].rm_so || off[0].rm_eo != strlen(device_name))
+				if (result || off[0].rm_so
+				 || ((int)off[0].rm_eo != (int)strlen(device_name))
+				) {
 					goto next_line;
+				}
 			}
 
 			/* This line matches: stop parsing the file