Make sure to set LANG variable before running tests

[ismail]

We should set LANG variable to a UTF-8 capable locale so we can run idn tests correctly.
Fixes #1277

[mention-bot]

@ismail, thanks for your PR! By analyzing the history of the files in this pull request, we identified @bagder, @yangtse and @dfandrich to be potential reviewers.

[dfandrich]

Setting LANG in runtests.pl isnt' the right approach since it means we're unable to run tests in other locales. This has caused problem in the past (e.g. the Turkey locale is particularly tricky). Since this only affects certain tests, it should be solved in the same way as test165, by setting environment variables specifically in the tests.

[ismail]

@dfandrich What do you mean by "unable to run tests in other locales" ? We force a locale for the test, even if you have tr_TR.UTF-8 locale all tests should pass since they run under a fixed locale.

Of course I can make the change for the specific tests only, I just didn't understand the problem you mention.

[dfandrich]

curl should run fine for people in any locale, and to help ensure that we need to be able to run the test suite in any locale. This patch forces all tests to run in one specific locale, meaning that we can no longer test curl in any others. Since only a few tests are actually locale-specific, only those specific ones should be forced to run in a fixed locale so that the remaining tests can still be tested in other locales.

[ismail]

@dfandrich Ah that makes sense, I'll redo the change. Thanks!

[ismail]

Let's retry with another request.