Never pass a `char' to a ctype function. I had relied on gcc -Wall

letting me know about instances of this, but it turns out that my
ctype.h explicitly casts input values to `int' to evade the
`subscript has type char' warning, so it had been carefully not
letting me know! Found them all by compiling with a doctored
ctype.h, and hopefully fixed them all too.

[originally from svn r2927]

ldisc.c

@@ -164,8 +164,8 @@ void ldisc_send(void *handle, char *buf, int len, int interactive)
 			bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 		    ldisc->buflen--;
 		    if (ldisc->buflen > 0 &&
-			isspace(ldisc->buf[ldisc->buflen - 1]) &&
-			!isspace(ldisc->buf[ldisc->buflen]))
+			isspace((unsigned char)ldisc->buf[ldisc->buflen-1]) &&
+			!isspace((unsigned char)ldisc->buf[ldisc->buflen]))
 			break;
 		}
 		break;

proxy.c

@@ -281,15 +281,15 @@ static int proxy_for_destination (SockAddr addr, char *hostname, int port,
 
     while (exclude_list[s]) {
 	while (exclude_list[s] &&
-	       (isspace(exclude_list[s]) ||
+	       (isspace((unsigned char)exclude_list[s]) ||
 		exclude_list[s] == ',')) s++;
 
 	if (!exclude_list[s]) break;
 
 	e = s;
 
 	while (exclude_list[e] &&
-	       (isalnum(exclude_list[e]) ||
+	       (isalnum((unsigned char)exclude_list[e]) ||
 		exclude_list[e] == '-' ||
 		exclude_list[e] == '.' ||
 		exclude_list[e] == '*')) e++;
@@ -325,7 +325,7 @@ static int proxy_for_destination (SockAddr addr, char *hostname, int port,
 
 	/* Make sure we really have reached the next comma or end-of-string */
 	while (exclude_list[s] &&
-	       !isspace(exclude_list[s]) &&
+	       !isspace((unsigned char)exclude_list[s]) &&
 	       exclude_list[s] != ',') s++;
     }
 

rlogin.c

@@ -169,7 +169,7 @@ static char *rlogin_init(void *frontend_handle, void **backend_handle,
 	sk_write(rlogin->s, cfg->termtype,
 		 strlen(cfg->termtype));
 	sk_write(rlogin->s, "/", 1);
-	for (p = cfg->termspeed; isdigit(*p); p++) continue;
+	for (p = cfg->termspeed; isdigit((unsigned char)*p); p++) continue;
 	sk_write(rlogin->s, cfg->termspeed, p - cfg->termspeed);
 	rlogin->bufsize = sk_write(rlogin->s, &z, 1);
     }

unix/uxstore.c

@@ -80,7 +80,7 @@ void provide_xrm_string(char *string)
     memcpy(key, p, q-p);
     key[q-p-1] = '\0';
     xrms->key = key;
-    while (*q && isspace(*q))
+    while (*q && isspace((unsigned char)*q))
 	q++;
     xrms->value = dupstr(q);