Set frame_unwind.stop_reason field to default_frame_unwind_stop_reason function.

2013-03-12  Anton Kolesov <akolesov@synopsys.com>

    * arc-tdep.c (arc_frame_unwind, arc_sigtramp_frame_unwind): set
    stop_reason field to default_frame_unwind_stop_reason function.
Merge branch 'arc_4_8-gdb-7_5_1-dev' of github.com:anthony-kolesov/arc_gdb into arc_4_8-gdb-7_5_1-dev