On x86, the 64-bit part of gnu/lib-names.h now says
# define LD_SO "ld.so.1"
(should be "ld-linux-x86-64.so.2") because the relevant information has moved to an x86_64 sysdeps directory, where it can no longer be found when gnu/lib-names.h is built for x86.
A fix is checked onto hjl/libnames branch at
I checked a fix into hjl/abi branch.