CYGWIN pgrename hacks fail

I successfully solved the remaining IPC problems on cygwin, but stumbled
upon new file operation problems.

At the bootstrap stage 1 XLogFileInit() fails at the rename step.
(xlog.c:1780)
post/dirmod.c is a very dirty piece of hack. cygwin shouldn't be that
that stupid. mingw maybe.

anyway, there's obviously a test mode, which doesn't compile.
post/dirmod cannot be compiled with -DFRONTEND
because pg_usleep is not defined on -DFRONTEND and __CYGWIN__

Any hints? who tested this?
The old pgrename version (7.4.5) worked just fine.
Now with the cygwin specific steps it fails.

e.g. In the debugger it says errno not defined. (dirmod.c:79)
errno is only defined in mingw.
--
Reini Urban
http://xarch.tu-graz.ac.at/home/rurban/