Fix ctype.h misuse.

Excluded: libtomath and libedit files, most of which appear to be
testing or example code not involved in production, and which are
derived from an upstream that should perhaps have patches submitted
upstream instead.

fix https://github.com/heimdal/heimdal/issues/1111

lib/gssapi/mech/gss_mech_switch.c

@@ -542,7 +542,8 @@ gss_name_to_oid(const char *name)
 	gss_OID oid = GSS_C_NO_OID;
 	size_t namelen = strlen(name);
 
-	if (isdigit(name[0]) && _gss_string_to_oid(name, &oid) == 0)
+	if (isdigit((unsigned char)name[0]) &&
+	    _gss_string_to_oid(name, &oid) == 0)
 		return oid;
 
 	_gss_load_mech();

lib/gssapi/netlogon/import_name.c

@@ -71,8 +71,8 @@ OM_uint32 _netlogon_import_name
 
     /* normalise name to uppercase XXX UTF-8 OK? */
     for (i = 0; i < len; i++) {
-        ((char *)name->NetbiosName.value)[i] =
-            toupper(((char *)name->NetbiosName.value)[i]);
+        ((unsigned char *)name->NetbiosName.value)[i] =
+            toupper(((unsigned char *)name->NetbiosName.value)[i]);
     }
 
     if (dnsName != NULL && dnsName[0] != '\0') {