Pure/elemental violation detection

[bolgrebolgre]

Changes in flang1:
(1) The severity was changed from 2 to 3 for pure attribute violation. (semant3.c, rest.c and semfin.c).
(2) A new error was added for the case when dummy arguments are not defined as intent(in) (semfin.c)
(3) A new error code 600 was added in errmsg-in.n for (2). The name of the dummy argument and the procedure who has violated the pure attribute are marked with color (brown-red).

Changes in runtime/flang/ieee_exception.F95 and ieee_arithmetic.F95 to remove pure/elemental violation errors during building process.

[bolgrebolgre]

Made a change in semfin.c to allow value attribute in pure procedures without using intent(in).

[kiranchandramohan]

@bolgrebolgre Can you consider rebasing this PR and making it ready for a review?

[bolgrebolgre]

@kiranchandramohan I will look into this. Would you mind if I start early next week? I am away from computer this week so probably difficult to work on this. Thanks!

[kiranchandramohan]

Thanks @bolgrebolgre for the reply. Yes, next week would be fine. We have a queue of PRs to review and work on. Was just going through the older PRs (like this one) to ensure they are also being considered.