Robert P. J. DAY says:

According to Mike Frysinger, this patch hasn't been necessary since
glibc-2.4+, so turf it from glibc patches 2.5 and up. If someone
complains, it can always go back in.

 # Compute x86_64-specific values

 CT_DoArchValues() {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}"

 }