Fix breakage for x86_64 static executables.

Yikes. Don't know how this slipped through code review.

I had actually mentioned a need for cleanup in this part of the build
system earlier, since the amount of duplication between
transform-o-to-* for each arch means we might fix things incorrectly
in one of them (as I've just shown). Similarly, code reviewers are
likely to skim each one after the first if they all look close enough
(which is presumably what happened here).

Change-Id: I9b85914510f0b114485021deb97f42740712aae5