Updated uses of the ctype function to support explict casting of the arguments

to (int)(unsigned char).

Target.cc

@@ -297,7 +297,7 @@ void Target::setHostName(char *name) {
     while (*p) {
       // I think only a-z A-Z 0-9 . and - are allowed, but I'll be a little more
       // generous.
-      if (!isalnum(*p) && !strchr(".-+=:_~*", *p)) {
+      if (!isalnum((int) (unsigned char) *p) && !strchr(".-+=:_~*", *p)) {
 	log_write(LOG_STDOUT, "Illegal character(s) in hostname -- replacing with '*'\n");
 	*p = '*';
       }