[patch] New toolchain: x86_64-pc-cygwin

[nick clifton]

Hi Corinna,

> bfd/ChangeLog:
>
> 	* config.bfd: Add x86_64-*-cygwin to list of supported targets.
>
> binutils/ChangeLog:
>
> 	* configure.in: Build DLL tools on x86_64-*-cygwin* as well.
> 	* configure: Regenerate.
>
> ld/ChangeLog:
>
> 	* configure.host: Add x86_64-*-cygwin* as valid host.
> 	* configure.tgt: Add x86_64-*-cygwin* as valid target.
> 	* emultempl/pep.em: Handle different requirements for Cygwin in terms
> 	of start addresses for executables and DLLs, based on memory model in
> 	http://cygwin.com/ml/cygwin-developers/2013-02/msg00027.html

Approved - please apply.

Cheers
   Nick