linux-user: Adjust child_tidptr on set_tid_address() syscall

linux-user: Adjust child_tidptr on set_tid_address() syscall

Keep track of the new child tidptr given by a set_tid_address() syscall.

Do not call the host set_tid_address() syscall because we are emulating
the behaviour of writing to child_tidptr in the exit() path.

Signed-off-by: Helge Deller<deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <YpH+2sw1PCRqx/te@p100>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>