Add front-end support for setting resouce limits.

The special value "user" means preserve the invoking user's limit.
The value "default" means don't override the default limit for the
user as assigned by the system (PAM, loging.conf, userdb, etc).

src/sudo.h

@@ -300,8 +300,10 @@ int tcsetpgrp_nobg(int fd, pid_t pgrp_id);
 void disable_coredump();
 void restore_limits(void);
 void restore_nproc(void);
+void set_policy_rlimits(void);
 void unlimit_nproc(void);
 void unlimit_sudo(void);
-int serialize_limits(char **info, size_t info_max);
+int serialize_rlimits(char **info, size_t info_max);
+bool parse_policy_rlimit(const char *str);
 
 #endif /* SUDO_SUDO_H */