[flang] Check int literals for overflow when kind is known.

improve test

Original-commit: flang-compiler/f18@09ce783cd30e6d70829d0b5596fe8f3e0f88c64f
Reviewed-on: https://github.com/flang-compiler/f18/pull/352
Tree-same-pre-rewrite: false
13 files changed
tree: 2179a5cc84b4e19cbf98388866a82760dbd908ee
  1. flang/