Added a private tls.h file with definitions for the reserved TLS slots.

Renamed i386_set_kstack() to i386_set_tss_and_kstack(), because that's what
it does.
Added a new function arch_thread_init_tls() which must be called after
having allocated the TLS area.
Renamed arch_thread_initialize_kthread_stack() to arch_thread_init_kthread_stack()
to be more consistent.
Changed the parameters for arch_thread_enter_uspace() - it now gets a pointer
to the thread structure and takes the user stack pointer from there (which
might also be architectural different).


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@2379 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/arch/x86/descriptors.h

@@ -94,7 +94,7 @@ set_segment_descriptor(struct segment_descriptor *desc, addr base, uint32 limit,
 	desc->present = 1;
 	desc->granularity = 1;	// 4 GB size (in page size steps)
 	desc->available = 0;	// system available bit is currently not used
-	desc->d_b = 1;
+	desc->d_b = 1;			// 32-bit code
 
 	desc->zero = 0;
 }