[Issue 18789] std.stdio messes up UTF conversions on output

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18789

--- Comment #2 from github-bugzilla at puremagic.com ---
Commit pushed to master at https://github.com/dlang/phobos

https://github.com/dlang/phobos/commit/d5cc4c5087a1819ac716cb5ea11d988fa667f822
fix conversion from wchar to char in LockingTextWriter.put

Fixes the easier part of issue 18789.

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