Add #include <locale>.  Refs #4700.

svn path=/trunk/boost/format/; revision=80987
Reduce code bloat from boost::format.  Fixes #4700.

svn path=/trunk/boost/format/; revision=80989
Fix for Ticket #7435: Crash with format using UTF16 strings on MacOS X. Reporter: Franz Detro.
https://svn.boost.org/trac/boost/ticket/7435

svn path=/trunk/boost/format/; revision=83374