Win32:

* Mostly, casting etc to remove compilation warnings in win32 only code.

* main.c: set _IONBF to stdout/stderr under win32 (under win32, _IOLBF
defaults to full buffering)

* pg_resetxlog/Makefile: ensures dirmod.o gets cleaned (got bitten by
this when, after "make clean"ing, switching compilation between Ming +
Cygwin)

Claudio Natoli