Previous version used type erasure through a `void* (*)()` pointer,
which triggered gcc warning and implied a lot of reinterpret_cast.
This version should make it harder to hit ourselves in the foot.
Differential revision: https://reviews.llvm.org/D54203
llvm-svn: 346522
2. Added argument to instruction scheduler creators so the creators can do
special things.
3. Repaired target hazard code.
4. Misc.
More to follow.
llvm-svn: 29450
