patch applied (ghc): partial fix for #1119

[Simon Marlow]

Tue Mar 27 08:22:15 PDT 2007  Simon Marlow <simonmar at microsoft.com>
  * partial fix for #1119
  Unless we're in one-shot mode, emit an error if we attempt to
  demand-load interfaces for home modules.  This can only happen in one
  way (that I'm aware of): typing a qualified name at the GHCi prompt
  that refers to a module that isn't loaded.  Previously you got a
  cryptic message about not finding an interface file, now you get:
  
  Prelude> Foo.a
  
  <interactive>:1:0:
      attempting to use module `Foo' (Foo.hs) which is not loaded
  
  Of course you can still refer to package modules like this without
  loading them explicitly, only home modules are affected, and the
  behaviour is exactly the same as if you try to ':browse Foo' and
  Foo isn't loaded.

    M ./compiler/iface/LoadIface.lhs -18 +25