Fixing break on cygwin because local_free_on_destruction.hpp is not included. Ticket #10137.

Cleans up the system_error_category::message function a bit to not have so many different ifdef paths. Now it is either using FormatMessageW on CE, WinRT, or if BOOST_NO_ANSI_APIS is defined. Otherwise FormatMessageA is used.
Where'd this code go?