port to x32 psABI (https://sites.google.com/site/x32abi/)
It's a "regular" x86-64 but with 32bit pointer size, and thus needs almost no change in ROOT.
To build, better get yourself a pre-built image e.g. from here http://www.gentoo.org/news/20120608-x32_abi.xml as the whole tool chain needs to be x32 capable:
	- linux-headers-3.4
	- binutils-2.22
	- glibc-2.15 (and will have stable glibc-2.16)
	- gcc-4.7.0
	- strace-4.7
	- gdb-7.4.1
NOTE: x32 #defines __ILP32__ *and* __x86_64__ i.e. for ROOT, R__B64 is defined.


git-svn-id: http://root.cern.ch/svn/root/trunk@45958 27541ba8-7e3a-0410-8455-c3a389f83636