[Attributor] Add AAExecutionDomainInfo interface to OpenMPOpt

Summary:
Add the AAExecutionDomainInfo attributor instance to OpenMPOpt.
This will infer information relating to domain information that an
instruction might be expecting in. Right now this only includes a very
crude check for instructions that will be executed by the master thread
by comparing a thread-id function with a constant zero.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D101578