Building an x86_64-linux-gnux32 (x32) gcc wiki page

[Martin Jambor]

Hi,

I have spent quite some time trying to build an x32 gcc to debug a PR
this week before I finally found the configure switch that made
everything work.  In order to share this possibly valuable knowledge,
I have created a wiki mini-page detailing how I managed to get it
finally working:

https://gcc.gnu.org/wiki/SettingUpX32GCC

I've linked it from the "Tutorials, HOWTOs" section of the
GettingStarted page because I did not find a better place.  Of course,
feel free to correct any mistakes I might have made.

Martin