radeon+libdrm-radeon: change relocation informations

Relocation now consist of the following informations (in this order) :
handle          buffer object handle identifier
start_offset    start offset of first data of the buffer object used by the cs
end_offset      end offset of last data of the buffer object used by the cs
read_domain     read domain (either VRAM, or GTT as GPU is invalid for CS)
write_domain    write domain (either VRAM, or GTT as GPU is invalid for CS)
flags           flags used for further optimization (like discard previous
                buffer content or forget buffer content after cs which can
                help in avoiding moving content in or out)