Moved the tss_descriptor structure to descriptor.h, updated it to be a
segment_descriptor structure, and provided inlines for set_tss_descriptor(),
set_segment_descriptor(), set_segment_descriptor_base(), and
clear_segment_descriptor().
Also added defines for the different privilege levels and descriptor types.
Removed the unusused and incorrect TSS definition, introduced new
TSS_BASE_SEGMENT and TLS_BASE_SEGMENT macros.
Removed include of arch/cpu.h in arch_cpu.h.
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@2360 a95241bf-73f2-0310-859d-f6bbb57e9c96
7208e95f0e