LLVM 9 drops the `TerminatorInst` class. This commit replaces it with
`Instruction` where possible and asserts
`Instruction::isTerminator()`. It also switches from
`TerminatorInst::successors` to `successors(TerminatorInst *)`.
* `GeneratedCodeBasicInfo::getCSVUsedByHelperCall` and
`GeneratedCodeBasicInfo::extractCSVs`: make the call argument an
`Instruction`.
* Introduce `blockByName`
* Introduce `getUniqueUser`.
* Fix linking issues.
This commit introduces the `enforce-abi` pass, which consumes the
information provided by the ABI analysis and enforces them in the
isolated functions adding actual arguments.
This commit also rewrites the logic of `ResultsPool::finalize` and
changes the semantic of `Yes` statements on arguments to `YesOrDead`.
Alessandro Di Federico