Platforms update

This PR is first step in include/header fixing.
First three commits clear and update xbmc_arch.m4, configure.in and makefiles.
For all posix platforms `xbmc/posix` is added to includes path. For darwin platforms `xbmc/darwin` is added to includes path, for android - `xbmc/android`, for freebsd - `xbmc/freebsd`.
Last commits move all "HAVE_*" and "HAS_*" macros to platform specific "PlatformConfig.h" and explicitly include "PlatformConfig.h" in **every** file that require any such macro. This will ensure that macros are always be defined regardless of future changes of headers.