Patch for 1.8.3p4 Win32 compile problems

Replying to intrevis:

This also fixes compile errors that would occur on systems without OpenSSL or without writev().

The changes to the project file all failed when I applied the patch; can you attach a copy of the updated file?

Otherwise, it's in (With some changes: The win32 mainthread() function returns int just like main(), so we can return exit codes instead of exit() (I'm too lazy to change the existing lines where main()/mainthread() uses exit(), though), and I cleaned up the shutdown message code to avoid always having to recalculate the translation and its length.)

(Oh, and I'm glad I checked in my Windows-to-Unix path separator script into svn)

I wonder if I can convince Win32 patch to emit Unix style path separators...