Remove unused `ios_info::datetime_flags` declaration and add test for `ios_info`

[codecov[bot]]

Codecov Report

Merging #133 (4ab566a) into develop (7386fd0) will increase coverage by 0.20%. The diff coverage is 100.00%.

Additional details and impacted files

[](https://codecov.io/gh/boostorg/locale/pull/133?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg) ```diff @@ Coverage Diff @@ ## develop #133 +/- ## =========================================== + Coverage 87.80% 88.01% +0.20% =========================================== Files 103 104 +1 Lines 9036 9184 +148 =========================================== + Hits 7934 8083 +149 + Misses 1102 1101 -1 ``` | [Impacted Files](https://codecov.io/gh/boostorg/locale/pull/133?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg) | Coverage Δ | | |---|---|---| | [include/boost/locale/formatting.hpp](https://codecov.io/gh/boostorg/locale/pull/133/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-aW5jbHVkZS9ib29zdC9sb2NhbGUvZm9ybWF0dGluZy5ocHA=) | `100.00% <100.00%> (+0.85%)` | :arrow_up: | | [src/boost/locale/shared/formatting.cpp](https://codecov.io/gh/boostorg/locale/pull/133/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-c3JjL2Jvb3N0L2xvY2FsZS9zaGFyZWQvZm9ybWF0dGluZy5jcHA=) | `90.76% <100.00%> (ø)` | | | [test/test\_ios\_info.cpp](https://codecov.io/gh/boostorg/locale/pull/133/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-dGVzdC90ZXN0X2lvc19pbmZvLmNwcA==) | `100.00% <100.00%> (ø)` | | ------ [Continue to review full report at Codecov](https://codecov.io/gh/boostorg/locale/pull/133?src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://codecov.io/gh/boostorg/locale/pull/133?src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg). Last update [7386fd0...4ab566a](https://codecov.io/gh/boostorg/locale/pull/133?src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg).