Cygwin: user profile: Make an effort to unload unused user profiles

Does this work?  There's not much feedback given.

TODO: We might want to try unloading the user profile at process
exit as well, FWIW.

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

winsup/cygwin/sec_auth.cc

@@ -306,6 +306,12 @@ load_user_profile (HANDLE token, struct passwd *pw, cygpsid &usersid)
   return pi.hProfile;
 }
 
+bool
+unload_user_profile (HANDLE token, HANDLE profile)
+{
+  return UnloadUserProfile (token, profile);
+}
+
 HANDLE
 lsa_open_policy (PWCHAR server, ACCESS_MASK access)
 {