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

*** 96,105 ****
--- 96,132 ----
          { USERATTR_AUDIT_FLAGS_KW, check_auditflags, auditflags },
  };
  
  #define NKEYS   (sizeof (keys)/sizeof (ua_key_t))
  
+ /* Import default keys for ordinary useradd */
+ void
+ import_def(struct userdefs *ud)
+ {
+         int i;
+ 
+         /* Don't import the user type (skip i = 0) */
+         for (i = 1; i < NKEYS; i++) {
+                 if (keys[i].newvalue == NULL)
+                         keys[i].newvalue =
+                             userdef_get_by_uakey(ud, keys[i].key);
+         }
+ }
+ 
+ /* Export command line keys to defaults for useradd -D */
+ void
+ update_def(struct userdefs *ud)
+ {
+         int i;
+ 
+         for (i = 0; i < NKEYS; i++) {
+                 if (keys[i].newvalue != NULL)
+                         userdef_set_by_uakey(ud, keys[i].key,
+                             keys[i].newvalue);
+         }
+ }
+ 
  /*
   * Change a key, there are three different call sequences:
   *
   *              key, value      - key with option letter, value.
   *              NULL, value     - -K key=value option.