Add checks for allocation errors, cleanup and report failure when they
occur.

* ast_duplicate_acl_list: Replace log warnings with errors, add missing
  line-feed.
* ast_append_acl: Add missing line-feed to logger message.
* ast_append_ha: Avoid ast_strdupa in loop by moving debug message to
  separate function.
* ast_ha_join: Use two separate calls to ast_str_append to avoid using
  ast_strdupa in a loop.

Change-Id: Ia19eaaeb0b139ff7ce7b971c7550e85c8b78ab76