- Split Windows CP "guessing" from real system charset determination

I've really had enough with this broken thing.

(at least: i= is mandatory, TTL notation is forbidden for IPv6)

- added controlled symbol export support for win32. Now, all visible symbols in libvlc.dll must be declared using either VLC_EXPORT or VLC_PUBLIC_API. Otherwise, they will not be exported. this has the advantage of reducing the number of symbols in the DLL, saving on file size an binding time at runtime. All exported symbols will be listed in the libvlc.def file.
This also pave the way for using the visibility feature in GCC 4, adding controlled symbols export for UNIX/MacOS X as well.

The scheme I used sucked big times.

- move vlm to input/
- remove unused libvlc export

* libvlc sources and plugins now define __LIBVLC__ and headers exported to
  plugins (ie, include/vlc_*.h) check for this
* libvlc sources use the value of the "libvlc" component in vlc-config instead
  of vlc
* Apply flags directly to "libvlc" in configure.ac - might temporarily break win32 :)

It made little sense to have an header that can only be included
in a single file.
Re-use libvlc.h for generic libvlc internal declarations.

* Headers in include must contain the structures and prototypes needed
  by the plugins and should be named vlc_*.
* Headers in include/vlc must contain the structures and prototypes
  needed by external libvlc clients

* Moved and renamed some things in headers. 
   - Removed vlc_cpu.h, vlc_error.h (merged in vlc_common)
   - Removed snapshot.h (merged in vlc_vout.h)
   - Removed vlc_spu.h (merged in vlc_osd.h)
   - Removed intf_eject.h and vlc_interaction.h (merged in vlc_interface)
   - Moved all internal headers to src
   - Merged vlc_video.h and video_output.h and move private things to src
   - Removed vlc/intf.h, vlc/aout.h, vlc/vout.h, vlc/decoder.h and vlc/input.h
     (meta headers for use in modules, and often implying too large 
     dependencies)
* Removed some useless dependencies
* Unexported a bunch of functions and structures used only in src/
  (--> Still some work here)
* Finally made input_thread_t and input_source_t (mostly) private. 
  Added input_GetItem to fetch the input_item of an input_thread
* Cleaned up deprecated entries in vlc_symbols.h and bumped up symbol 
  prefix

This commit has a 99% probability of breaking the build, 0.1% of killing
your cat and 0% of getting you hot chicks.

(vlc 0.9.0 is definitely not going to be ABI-compatible with 0.8.6).

The libvlc.so ABI is still way too unstable IMHO.

This commit will probably break havoc in bindings in the short term,
but hey, this is the unstable branch

(of course, it was obvious reverting the earlier fix would break it,
 but some people don't seem to care about the build system as long as
 "their" feature works).
Oh, and don't let version.c twice in CLEANFILES.