Split locale management out of newlib/xlocale.h. NFCI

This is one part of many of a locale refactor. See
http://reviews.llvm.org/D17146 for an idea of where this is going.

For the locale refactor, the locale management functions (newlocale,
freelocale, uselocale) are needed in a separate header from the various _l
functions. This is because some platforms implement the _l functions in terms
of a locale switcher RAII helper, and the locale switcher RAII helper needs
the locale management functions. This patch helps pave the way by getting all
the functions in the right files, so that later diffs aren't completely

The "do-nothing" / "nop" locale functions are also useful on their own for
other lightweight platforms. Putting these nop implementations in
support/xlocale should enable code sharing.

Unfortunately, I have no access to a newlib system to build and test with, so
this change has been made blind.

Reviewed: http://reviews.llvm.org/D17382

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@261231 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed