This patch adds the definitions for the operations and attributes (just
one enum attribute) for the `index` dialect.
Depends on D135688
Reviewed By: rriddle, jpienaar
Differential Revision: https://reviews.llvm.org/D135689
This patch introduces the `index` dialect and associated boilerplate for
adding ops and enums (comparison predicates).
Reviewed By: rriddle, jpienaar, nicolasvasilache
Differential Revision: https://reviews.llvm.org/D135688