LaTeX export: Fix another problem with #+AUTHOR export

LaTeX export: Fix another problem with #+AUTHOR export

Jambunathan K. writes:

> I would like to add the following observation as well -
>
> ---> org input <---
> #+AUTHOR: Jambunathan K\cr\href{mailto:{{{EMAIL}}}}{{{{EMAIL}}}}
>
> ---> actual tex output <---
> \author{Jambunathan K\cr\href{mailto:kjambunathan@gmail.com}\{kjambunathan@gmail.com\}}
>
> The above tex snippet has the effect of getting the "Url Box" wrong.
>
> I was hoping to produce the following line -
> \author{Jambunathan K\cr\href{mailto:kjambunathan@gmail.com}{kjambunathan@gmail.com}}
>
> Generally speaking, macro expansion in author string behaves strangely.