Add libuserdefs and use in cmd/{oamuser,passwd}

*** 41,50 ****
--- 41,53 ----
  
  char *getusertype(char *cmdname);
  
  int is_role(char *usertype);
  
+ struct userdefs;
+ void import_def(struct userdefs *ud);
+ void update_def(struct userdefs *ud);
  void change_key(const char *, char *);
  void addkey_args(char **, int *);
  char *getsetdefval(const char *, char *);
  
  extern int nkeys;