This didn't work on Windows because wchar_t is 2 bytes on that
platform, not 4 bytes (whereas llwchar is 4 bytes everywhere).
Boost's regex methods need to work on wchar_t, but I believe
that using a UTF-16 string would still be prone to crashing on
Windows as UTF-16 is still a variable-length encoding. Besides,
trying to compile a UTF-16 solution generates weird link errors.

Instead, I'm going to fix this problem a different way. And
I'm starting by reverting the previous attempt. Thanks Win32.