[PATCH] Add hasUnderlyingType narrowing matcher for TypedefDecls

[Richard]

In http://reviews.llvm.org/D8149#157110, @klimek wrote:

> Argh, sorry for missing it - please always feel free to ping earlier (especially my reviews you can ping 2x per week).
>  Can you please add a unit test? Apart from that it looks good.


I added a `FileCheck` test in the tools-extra repository (see http://reviews.llvm.org/D8150).  Is that sufficient, or would you also like to see a unit test?


http://reviews.llvm.org/D8149

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