First step to remove CONFIG_VTI for final supporting xen0+xenU+xenVTI at runtime...

First step to remove CONFIG_VTI for final supporting xen0+xenU+xenVTI at runtime. This changeset mainly addresses common code like domain creation and rid allocation policy, including:

- Boot time vti feature detection
- Uniform arch_do_createdomain, new_thread, arch_set_infoguest, and construct_dom0. Now these function level CONFIG_VTIs have been removed with several specific lines still protected by CONFIG_VTIs. With more feature cleanup later, these lines will be free out grandually.
- Use same rid allocation policy including physical emulation
- Remove duplicated definition rr_t.

Verified breaking nothing. ;-)

Signed-off-by Kevin Tian <kevin.tian@intel.com>