NPTL/arc: notify kernel of the TP value

NPTL/arc: notify kernel of the TP value

Native gdb makes a ptrace (GET_THREAD_AREA) which needs to return the
TP. however when libc sets up TP reg (for main thread), it doesn't call
arc_settls syscall so kernel doesn't know of TP register details
(moreso because clone doesnt have SETTLS flag)

Note that kernel doesn't know about r25 being TP etc.

This commit got lost in merge of NPTL tools into arc-mainline-dev and
showed up again as STAR 9000919529 (native gdb can't debug threaded
apps)

	------->8---------------
	[ARCLinux]# gdb ./pth
	Reading symbols from ./pth...(no debugging symbols found)...done.
	(gdb) b main
	Breakpoint 1 at 0x106f2
	(gdb) r
	Starting program: /pth
	[Thread debugging using libthread_db enabled]
	Using host libthread_db library "/lib/libthread_db.so.1".
	thread_get_info_callback: cannot get thread info: generic error
	(gdb) q
	------->8---------------
Debugged-by: Anton Kolesov <akolesov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>