Try best to handle user from domain not in trusted domain list.

* cygheap.h (cygheap_domain_info::add_domain): Add prototype.
	* uinfo.cc (cygheap_domain_info::add_domain): New method.
	(pwdgrp::fetch_account_from_windows): Try to add domain explicitely
	if it was not in the original list of trusted domains and go ahead
	rather than bailing out.  Add comment to explain why.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/cygheap.h

@@ -393,6 +393,7 @@ public:
 
   inline PDS_DOMAIN_TRUSTSW trusted_domain (ULONG idx) const
     { return (idx < tdom_count) ? tdom + idx : NULL; }
+  PDS_DOMAIN_TRUSTSW add_domain (PCWSTR, PSID);
 
   inline PWCHAR get_rfc2307_domain () const
     { return rfc2307_domain_buf ?: NULL; }