1.0.28.52: fix x86-64 build, oops

1.0.28.52: fix x86-64 build, oops

  Name data vector accessor VOPs consistently, using the -WITH-OFFSET/
  style names, since on x86-64 they all are with offsets.
  (INITIALIZE-VECTOR has a macrolet that generates VOP calls based on
  the platform, and wants consistent names.)