ia64: use PTRACE_GETREGS to fetch registers

ia64: use PTRACE_GETREGS to fetch registers

* linux/ia64/arch_regs.h: Stop including <asm/rse.h>.
(ia64_frame_ptr): New declaration.
* signal.c (sys_sigreturn) [IA64]: Use ia64_frame_ptr.
* syscall.c [IA64]: Include <asm/rse.h>.
[IA64] (ia64_regs, ia64_frame_ptr): New variable.
[IA64] (ARCH_REGS_FOR_GETREGS): New macro.
[IA64] (ia64_ia32mode): Convert to macro.
[IA64] (ia64_r8, ia64_r10): Remove.
(getrval2, print_pc, get_scno, get_syscall_args, get_error) [IA64]:
Use ia64_regs.
(get_syscall_result) [IA64]: Remove.