I do not think GNU awk specifies the array iteration order. The enum type with the tunables indices is defined like this:

  # Now, the enum names
  print "\ntypedef enum"
  print "{"
  for (tnm in types) {
    split (tnm, indices, SUBSEP);
    t = indices[1];
    n = indices[2];
    m = indices[3];
    printf ("  TUNABLE_ENUM_NAME(%s, %s, %s),\n", t, n, m);
  }
  print "} tunable_id_t;\n"

So the assigned indices depend on array iteration order.

This could be a problem if building glibc multilibs (for glibc-hwcaps), where the (baseline) ld.so and multilib libc.so.6 come from different builds and have potentially different iteration order. This can cause crashes because __tunable_get_val does not perform any type checking. It may store a larger tunable value than the caller specifies through the value pointer, causing memory corruption.