Move ozone platform files to platform\

This patch moves ozone_platform* files to under platform\,
so we have same folder structure as other ozone
implementations.
Fix shared_component build for Ozone platform.

This patch makes necessary changes in Ozone Wayland code
base to fix shared_component build. It introduces
OZONE_WAYLAND_EXPORT macro to make the needed symbols
visible outside ozone.so.