Fix nto,spu and win32 builds of GDBServer.

Fix nto,spu and win32 builds of GDBServer.

This patch fixes the build that was broken by :
https://sourceware.org/ml/gdb-patches/2015-10/msg00369.html

It implements the sw_breakpoint_from_kind operation on these targets and removes
the calls to set_breakpoint_data.

Compiliation tested on win32.

Not tested : nto, spu.

gdb/gdbserver/ChangeLog:

	* nto-low.c (nto_sw_breakpoint_from_kind): New function.
	(struct target_ops) <sw_breakpoint_from_kind>: Initialize.
	(initialize_low): Remove set_breakpoint_data call.
	* spu-low.c (spu_sw_breakpoint_from_kind): New function.
	(struct target_ops) <sw_breakpoint_from_kind>: Iniitalize.
	(initialize_low): Remove set_breakpoint_data call.
	* win32-low.c (win32_sw_breakpoint_from_kind): New function.
	(struct target_ops) <sw_breakpoint_from_kind>: Initialize.
	(initialize_low): Remove set_breakpoint_data call.