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/coreutils/expand.c b/coreutils/expand.c
index a7ac8ea..af2ef86 100644
--- a/coreutils/expand.c
+++ b/coreutils/expand.c
@@ -41,7 +41,7 @@
 	char *line;
 	char *ptr;
 	int convert;
-	int pos;
+	unsigned pos;
 
 	/* Increment tab_size by 1 locally.*/
 	tab_size++;
@@ -80,7 +80,7 @@
 	int convert;
 	int pos;
 	int i = 0;
-	int column = 0;
+	unsigned column = 0;
 
 	while ((line = xmalloc_fgets(file)) != NULL) {
 		convert = 1;