[PATCH] [libc++] Support Newlib as libc++'s C library [locale part 2]

[Jonathan Roelofs]

This is waaay not thread safe. The right way to fix all of this is to implement the *_l functions in newlib, and skip all of this awkward and not-so-correct shim business.

For now it makes more sense to just xfail the tests that would otherwise need this.

http://reviews.llvm.org/D5418