[Issue 17961] std.uni does not compile with -unittest -dip1000

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17961

--- Comment #5 from hsteoh at quickfur.ath.cx ---
Yeah, I know Phobos is not -dip1000 ready yet.  That's probably how this PR got
pulled in spite of the breakage. :-P

It would be nice to fix these breakages, though.  Less trouble for when we do
want to start building Phobos with -dip1000.

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