hurd: add TLS support

hurd: add TLS support

	* sysdeps/generic/thread_state.h (MACHINE_NEW_THREAD_STATE_FLAVOR):
	Define macro.
	* sysdeps/mach/thread_state.h (MACHINE_THREAD_STATE_FIX_NEW): New macro.
	* sysdeps/mach/i386/thread_state.h
	(MACHINE_NEW_THREAD_STATE_FLAVOR): New macro, defined to
	i386_THREAD_STATE.
	(MACHINE_THREAD_STATE_FLAVOR): Define to i386_REGS_SEGS_STATE instead of
	i386_THREAD_STATE.
	(MACHINE_THREAD_STATE_FIX_NEW): New macro, reads segments.

	* sysdeps/mach/hurd/i386/trampoline.c (_hurd_setup_sighandler): Use
	i386_REGS_SEGS_STATE instead of i386_THREAD_STATE.

	* sysdeps/mach/hurd/i386/tls.h (TCB_ALIGNMENT, HURD_SEL_LDT): New
	macros.
	(_hurd_tls_fork): Add original thread parameter, Duplicate existing LDT
	descriptor instead of creating a new one.
	(_hurd_tls_new): New function, creates a new descriptor and updates tcb.

	* mach/setup-thread.c: Include <ldsodefs.h>.
	(__mach_setup_thread): Call _dl_allocate_tls, pass
	MACHINE_NEW_THREAD_STATE_FLAVOR to __thread_set_state instead of
	MACHINE_THREAD_STATE_FLAVOR, before getting
	MACHINE_THREAD_STATE_FLAVOR, calling _hurd_tls_new, and setting
	MACHINE_THREAD_STATE_FLAVOR with the result.
	* hurd/hurdfault.c (_hurdsig_fault_init): Call
	MACHINE_THREAD_STATE_FIX_NEW.
	* sysdeps/mach/hurd/fork.c (__fork): Call _hurd_tls_fork for sigthread
	too.  Add original thread parameter.