[libcxx-commits] [clang] [libcxx] [libc++] Rename `__` prefix to `__libcpp_` for locale related functions (PR #119241)

[Sean Perry via libcxx-commits]

perry-ca wrote:

These macros can't be undef'ed as they are used to implement the functions like islower(int) by the headers like ctype.h.  Any name other than __X will work for these inline functions in libc++.

https://github.com/llvm/llvm-project/pull/119241