[Patch] Minor name lookup related tweaks.

Hi,

Attached is small patch, which:
- Changes Lookup*Name functions to return NamedDecls, instead of
Decls. Unfortunately my recent statement that it will simplify lot of
code, was not quite right, but it simplifies some...
- Makes MergeLookupResult SmallPtrSet instead of vector, following
Douglas suggestions.
- Adds %qN format for printing qualified names to Diagnostic.
- Avoids searching for using-directives in Scopes, which are not
DeclScope, during unqualified name lookup.

Piotr

lookup.tweaks.diff (35.7 KB)

Committed here:

   http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090202/011746.html

Thanks!

  - Doug