Fix ICU boundary detection

[Flamefire]

With the fix for #44 in #154 a bug in older ICU versions (i.e. up to 54.x) is triggered by using the UTF-8 string in-place via UText*

test_boundary detects that but such ICU versions are rare due to the age.

• Restrict the optimization to ICU >= 55.2 which has the bug fixed
• Use RAII for UText*
• Fix test_formatting failures in older ICU versions after #184
• Fix a possible warning on MSVC caused by ICU headers

[codecov[bot]]

Codecov Report

Merging #185 (aa4031a) into develop (2ada5fe) will increase coverage by 0.04%. The diff coverage is 97.22%.

Additional details and impacted files

[](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg) ```diff @@ Coverage Diff @@ ## develop #185 +/- ## =========================================== + Coverage 92.74% 92.79% +0.04% =========================================== Files 112 112 Lines 9888 9897 +9 =========================================== + Hits 9171 9184 +13 + Misses 717 713 -4 ``` | [Impacted Files](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg) | Coverage Δ | | |---|---|---| | [src/boost/locale/icu/formatter.cpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-c3JjL2Jvb3N0L2xvY2FsZS9pY3UvZm9ybWF0dGVyLmNwcA==) | `78.78% <ø> (ø)` | | | [src/boost/locale/util/encoding.hpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-c3JjL2Jvb3N0L2xvY2FsZS91dGlsL2VuY29kaW5nLmhwcA==) | `100.00% <ø> (ø)` | | | [src/boost/locale/icu/boundary.cpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-c3JjL2Jvb3N0L2xvY2FsZS9pY3UvYm91bmRhcnkuY3Bw) | `93.75% <92.30%> (+3.65%)` | :arrow_up: | | [src/boost/locale/util/codecvt\_converter.cpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-c3JjL2Jvb3N0L2xvY2FsZS91dGlsL2NvZGVjdnRfY29udmVydGVyLmNwcA==) | `94.24% <100.00%> (+0.08%)` | :arrow_up: | | [test/test\_encoding.cpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-dGVzdC90ZXN0X2VuY29kaW5nLmNwcA==) | `97.49% <100.00%> (+0.08%)` | :arrow_up: | | [test/test\_formatting.cpp](https://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg#diff-dGVzdC90ZXN0X2Zvcm1hdHRpbmcuY3Bw) | `99.74% <100.00%> (ø)` | | ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/boostorg/locale/pull/185?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://app.codecov.io/gh/boostorg/locale/pull/185?src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=boostorg). Last update [2ada5fe...aa4031a](https://app.codecov.io/gh/boostorg/locale/pull/185?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).