login.c (destroy_tickets): Just use global kcontext instead

login.c (destroy_tickets): Just use global kcontext instead
      of creating a new krb5 context for no good reason.

krshd.c (main):
krsh.c (main):
krlogind.c (main):
krlogin.c (main):
krcp.c(main): Check the error return from krb5_init_context(),
      and print an error message if necessary.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@9317 dc483132-0cff-0310-8789-dd5450dbe970