Attached are two patches required to enable x32 support in the prelinker.  (And 
of course updates to your the local prelink.conf to add the x32 library directory.)

The first change 0001-... modifies the way the PL_ARCH is defined.  This patch 
has been used for a long time in the cross-prelinker work.  The patch was 
originally written as part of some Code Sourcery, LLC (now part of Mentor 
Graphics) work.  The purpose of it is to enable multiple architecture 
definitions within a single arch-...c file.

The second change relies on the first, and implements the x32 ABI specs.  Within 
the specs "https://sites.google.com/site/x32abi/documents/abi.pdf", both x86-64 
and x86-64 x32 are defined.  A new local define was added to switch between 
32-bit and 64-bit read/write operations based on the value of ELFCLASS32.

Please let me know if you have any questions, or if either of these needs any 
refactoring to be accepted in the upstream source.

Thanks!
--Mark