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