Refactor disassembly code

Refactor disassembly code

This patch addes class gdb_disassembler, and refactor
code to use it.  The gdb_disassembler object is saved
in disassember_info.application_data.  However,
disassember_info.application_data is already used by
gdb for arm, mips spu, and scm-disasm.  In arm and mips,
.application_data is gdbarch, but we can still get gdbarch
from gdb_disassember.

The use of application_data in spu is a little bit
complicated.  It creates its own disassemble_info, and
save spu_dis_asm_data in .application_data.  This will
overwrite the pointer to gdb_disassembler, so we need
to find another place to save spu_dis_asm_data.  I
extend disassemble_info, and put "id" there.

gdb:

2017-01-26  Pedro Alves  <palves@redhat.com>
	    Yao Qi  <yao.qi@linaro.org>

	* arm-tdep.c: Include "disasm.h".
	(gdb_print_insn_arm): Update code to get gdbarch.
	* disasm.c (dis_asm_read_memory): Change it to
	gdb_disassembler::dis_asm_read_memory.
	(dis_asm_memory_error): Likewise.
	(dis_asm_print_address): Likewise.
	(gdb_pretty_print_insn): Change it to
	gdb_disassembler::pretty_print_insn.
	(dump_insns): Add one argument gdb_disassemlber.  All
	callers updated.
	(do_mixed_source_and_assembly_deprecated): Likewise.
	(do_mixed_source_and_assembly): Likewise.
	(do_assembly_only): Likewise.
	(gdb_disassembler::gdb_disassembler): New.
	(gdb_disassembler::print_insn): New.
	* disasm.h (class gdb_disassembler): New.
	(gdb_pretty_print_insn): Remove declaration.
	(gdb_disassemble_info): Likewise.
	* guile/scm-disasm.c (class gdbscm_disassembler): New.
	(gdbscm_disasm_read_memory_worker): Update.
	(gdbscm_disasm_read_memory): Update.
	(gdbscm_disasm_memory_error): Remove.
	(gdbscm_disasm_print_address): Remove.
	(gdbscm_disassembler::gdbscm_disassembler): New.
	(gdbscm_print_insn_from_port): Update.
	* mips-tdep.c: Include disasm.h.
	(gdb_print_insn_mips): Update code to get gdbarch.
	* record-btrace.c (btrace_insn_history): Update.
	* spu-tdep.c: Include disasm.h.
	(struct spu_dis_asm_data): Remove.
	(struct spu_dis_asm_info): New.
	(spu_dis_asm_print_address): Use spu_dis_asm_info to get
	SPU id.
	(gdb_print_insn_spu): Cast disassemble_info to
	spu_dis_asm_info.