Since those features are general properties of the environment, it makes
sense to use them from libc++abi too, and so the name libcpp-has-no-xxx
doesn't make sense.
Differential Revision: https://reviews.llvm.org/D126482
When porting libc++ to embedded systems, it can be useful to drop support
for localization, which these systems don't implement or care about.
Differential Revision: https://reviews.llvm.org/D90072