gdbserver/linux-low: turn 'breakpoint_kind_from_{pc, current_state}' into methods

gdbserver/linux-low: turn 'breakpoint_kind_from_{pc, current_state}' into methods

gdbserver/ChangeLog:
2020-04-02  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	Remove the 'breakpoint_kind_from_pc' and
	'breakpoint_kind_from_current_state' linux target ops, and let the
	concrete linux target define them by overriding the ops of
	process_stratum_target.

	* linux-low.cc (linux_process_target::breakpoint_kind_from_pc):
	Remove.
	(linux_process_target::breakpoint_kind_from_current_state): Remove.
	* linux-low.h (struct linux_target_ops): Remove ops.
	(class linux_process_target) <breakpoint_kind_from_pc>: Remove.
	<breakpoint_kind_from_current_state>: Remove.
	* linux-x86-low.cc (the_low_target): Remove the op fields.
	* linux-bfin-low.cc (the_low_target): Ditto.
	* linux-cris-low.cc (the_low_target): Ditto.
	* linux-crisv32-low.cc (the_low_target): Ditto.
	* linux-m32r-low.cc (the_low_target): Ditto.
	* linux-m68k-low.cc (the_low_target): Ditto.
	* linux-mips-low.cc (the_low_target): Ditto.
	* linux-nios2-low.cc (the_low_target): Ditto.
	* linux-ppc-low.cc (the_low_target): Ditto.
	* linux-s390-low.cc (the_low_target): Ditto.
	* linux-sh-low.cc (the_low_target): Ditto.
	* linux-sparc-low.cc (the_low_target): Ditto.
	* linux-tic6x-low.cc (the_low_target): Ditto.
	* linux-tile-low.cc (the_low_target): Ditto.
	* linux-xtensa-low.cc (the_low_target): Ditto.
	* linux-aarch64-low.cc (class aarch64_target)
	<breakpoint_kind_from_pc>
	<breakpoint_kind_from_current_state>: Declare.
	(aarch64_breakpoint_kind_from_pc): Turn into...
	(aarch64_target::breakpoint_kind_from_pc): ...this.
	(aarch64_breakpoint_kind_from_current_state): Turn into...
	(aarch64_target::breakpoint_kind_from_current_state): ...this.
	(the_low_target): Remove the op fields.
	* linux-arm-low.cc (class arm_target):
	<breakpoint_kind_from_pc>
	<breakpoint_kind_from_current_state>: Declare.
	(arm_target::breakpoint_kind_from_pc): Define.
	(arm_target::breakpoint_kind_from_current_state): Define.
	(the_low_target): Remove the op fields.
	* linux-riscv-low.cc (class riscv_target):
	<breakpoint_kind_from_pc>: Declare.
	(riscv_breakpoint_kind_from_pc): Turn into...
	(riscv_target::breakpoint_kind_from_pc): ...this.
	(the_low_target): Remove the op fields.