[llvm] [Offload] Generate OffloadInfo.inc (PR #147316)

[Ross Brunton via llvm-commits]

RossBrunton wrote:

This is the first in several MRs to make the device information queries not depend on hardcoded strings. But having to generate an "inc" file every time we want to use an enum feels rather janky.

Is it worth having an "offload enums" header file that can be included by offload and contains all the enums for liboffload instead? Or even bite the bullet and have the plugin interface include OffloadAPI.h directly?

https://github.com/llvm/llvm-project/pull/147316