[Modules] Move the ConstantRange class into the IR library. This is
a bit surprising, as the class is almost entirely abstracted away from
any particular IR, however it encodes the comparsion predicates which
mutate ranges as ICmp predicate codes. This is reasonable as they're
used for both instructions and constants. Thus, it belongs in the IR
library with instructions and constants.

llvm-svn: 202838
GitOrigin-RevId: 8cd041ef195abc0d500c26fb08db123eacb60c1a
18 files changed