ctype: Cast arguments to unsigned char

Eliminates a warning about char subscripts on NetBSD.

The argument of these functions is of type int, but only a very
restricted subset of values are actually valid.  The argument must either
be the value of the macro EOF (which has a negative value), or must be a
non-negative value within the range representable as unsigned char.
Passing invalid values leads to undefined behavior.

Signed-off-by: Nia Alarie <nia@NetBSD.org>

Author: alarixnia

net.c

@@ -201,7 +201,7 @@ read_remote(int fd, int extbufsize, char *extbuf)
 		switch (parsestate) {
 		case parse_status:
 			for (; pos < len; pos++) {
-				if (isdigit(buff[pos])) {
+				if (isdigit((unsigned char)buff[pos])) {
 					status_running = status_running * 10 + (buff[pos] - '0');
 				} else {
 					status = status_running;

spool.c

@@ -181,7 +181,7 @@ readqueuef(struct queue *queue, char *queuefn)
 		*s = 0;
 
 		s++;
-		while (isspace(*s))
+		while (isspace((unsigned char)*s))
 			s++;
 
 		s = strdup(s);

util.c

@@ -83,7 +83,8 @@ hostname(void)
 		if (s == NULL)
 			goto local;
 
-		for (s = name; *s != 0 && (isalnum(*s) || strchr("_.-", *s)); ++s)
+		for (s = name; *s != 0
+		    && (isalnum((unsigned char)*s) || strchr("_.-", *s)); ++s)
 			/* NOTHING */;
 		*s = 0;
 
@@ -126,7 +127,8 @@ systemhostname(void)
 	 */
 	name[sizeof(name) - 1] = 0;
 
-	for (s = name; *s != 0 && (isalnum(*s) || strchr("_.-", *s)); ++s)
+	for (s = name; *s != 0 &&
+	    (isalnum((unsigned char)*s) || strchr("_.-", *s)); ++s)
 		/* NOTHING */;
 	*s = 0;