illumos gate

Remove an incorrect optimization. The type IDs of each member of a struct or
union must be checked when determine whether two types are equivalent. This
bug could cause ctfmerge(1) to incorrectly merge distinct types.

Consider

  struct a { int x, int y };

  struct b {int x, unsigned int y };

In this case, the code wasn't comparing the types of the "y" members,
since "x" and "y" have the same type in struct a. I'm not really sure
what optimization was being attempted there, but the code that's present
is wrong.