Relax ARM prologue unwinder assumption

Relax ARM prologue unwinder assumption

Modify the ARM prologue unwinder to use the stop_reason hook instead of
returning imprecise frame id's through the arm prologue this_id hook.

gdb/
2015-02-10  Luis Machado  <lgustavo@codesourcery.com>

	* arm-tdep.c (arm_prologue_unwind_stop_reason): New function.
	(arm_prologue_this_id): Move PC and SP limit checks to
	arm_prologue_unwind_stop_reason.
	(arm_prologue_unwind) <stop_reason> : Set to
	arm_prologue_unwind_stop_reason.