[krbdev.mit.edu #2028] autodisplay kfw kinit dialog from gssapi when there are no tickets

[Jeffrey Altman via RT]

As per Marshall, KfW should behave identically to KfM.  When calls to
gss_init_sec_context are made without valid tgts in the cache, the kinit
dialog should be displayed to the end user.  

This change will require changes to 

  /src/lib/krb5/ccache/ccdefault.c
  /src/lib/krb5/ccache/Makefile.in
  /src/config/win-pre.in

as well as an extension to the Leash API.