use dual paths on LD_LIBRARY_PATH to solve cross-arch execve

[derekbruening]

From [email protected] on May 23, 2009 10:47:57

xref issue #20 where we tweak the LD_LIBRARY_PATH on execve if the target is
a different arch

we may be able to avoid that by simply putting both lib32 and lib64 paths
on LD_LIBRARY_PATH, but first we should verify that ld on all platforms has
consistent behavior there

Original issue: http://code.google.com/p/dynamorio/issues/detail?id=145

[derekbruening]

Closing as this only works when using LD_PRELOAD and the system loader to load DR. That is not the case for today's early injection.