PR remote/1966

	PR remote/1966
	* dcache.c (dcache_write_line): Use target_write.
	(dcache_read_line): Use target_read.
	* mi/mi-main.c (mi_cmd_data_read_memory): Use target_read.
	* symfile.c (struct load_section_data): Add new per-section
	members.
	(load_progress): New function.
	(load_section_callback): Pass load_progress to the new
	target_write_with_progress.
	* target.c (current_xfer_partial, memory_xfer_partial): New.
	(target_xfer_partial): New prototype.
	(target_xfer_memory, target_xfer_partial_p, xfer_using_stratum)
	(do_xfer_memory, target_xfer_memory_partial)
	(target_read_memory_partial, target_write_memory_partial): Delete.
	(trust_readonly): Move higher in the file.
	(update_current_target): Use current_xer_partial.
	(target_xfer_partial): Use memory_xfer_partial.  Handle
	TARGET_OBJECT_RAW_MEMORY specially.
	(target_read_memory): Use target_read.
	(target_write_memory): Use target_write.
	(default_xfer_partial): Call to_xfer_partial directly.
	(target_write_with_progress): New function, based on target_write.
	(target_write): Call it.
	* target.h (enum target_object): Add TARGET_OBJECT_RAW_MEMORY.
	(target_write_with_progress): New prototype.
	(do_xfer_memory, target_read_memory_partial)
	(target_write_memory_partial): Delete prototypes.