cmake: Code clean up, set up options before we start including custom macros, add CONTRIB_INCLDE to CMAKE_REQUIRED_INCLUDES if ENABLE_CONTRIB is set, and correctly discover postproc/postprocess.h header by temporarily adding FFmpeg_CFLAGS to CMAKE_REQUIRED_FLAGS before checking for the header.

XvMC: remove warnings. The compilation problems lies in a confustion between subpicture_data_t from spudec.h and subpicture_sys_t. No idea how to fix.

XvMC: Compile Fixes, b_shm removal, and obvious typos... subpicture_sys_t still undeclared, no idea why it is around...

XvMC Vout: Fix the macroblocks_t definition. Still not compiling because of subpictures_sys_t not defined.

 - Fix ActiveX.

Lets wait for 0.9.1 to sort this out.

 - Remove useless system_VLCPath

XvMC: revert [25318] and do it in a better way. Remove some warnings because of forgotten inclusions.

This can cause needless I/O, and consistutes a trivial local privilege esclation.

If you packaged without staged installation you're going to have a problem (but packaging without staged installation is to utterly lame in the first place)