default fsenc patch

[Stephen J. Turnbull]

Martin Pool writes:

 > Yes, this issue only arises on non-Apple Unix.  On Windows and Mac OS
 > X the file name encoding is defined by the OS, independent of locale.

This isn't quite true for Mac OS X, at least as late as Leopard
(10.5).  Very low-level APIs do not enforce NFD UTF-8.

Not that I think you should do anything about it; anybody using such
APIs to write file names in a different encoding presumably knows what
they're doing and why.  Just in case any reader encounters it....