localedef during tests suddenly needs a lot of memory

[Florian Weimer]

With upstream master as of commit
bb6274ee1293a6bc76d9d7c889783303de181295, I see that make check in the
localedata subdirectory needs lots and lots of memory (several gigabytes).

Is this caused by the recent Unicode changes?  I'm worried that we need
a smarter algorithm for computing the locales.

Thanks,
Florian