Move tfile target to tracefile-tfile.c

Move tfile target to tracefile-tfile.c

This patch moves tfile target related code from tracepoint.c to
tracefile-tfile.c.

gdb:

2014-02-23  Yao Qi  <yao@codesourcery.com>

	* tracepoint.c (TFILE_PID): Move it to tracefile-tfile.c.
	(O_LARGEFILE): Likewise.
	(tfile_ops): Likewise.
	(TRACE_HEADER_SIZE): Likewise.
	(trace_fd, trace_frames_offset, cur_offset): Likewise.
	(cur_data_size): Likewise.
	(tfile_read, tfile_open, tfile_interp_line): Likewise.
	(tfile_close, tfile_files_info): Likewise.
	(tfile_get_trace_status): Likewise.
	(tfile_get_tracepoint_status): Likewise.
	(tfile_get_traceframe_address): Likewise.
	(tfile_trace_find, match_blocktype): Likewise.
	(traceframe_walk_blocks, traceframe_find_block_type): Likewise.
	(tfile_fetch_registers, tfile_xfer_partial): Likewise.
	(tfile_get_trace_state_variable_value): Likewise.
	(tfile_has_all_memory, tfile_has_memory): Likewise.
	(tfile_has_stack, tfile_has_registers): Likewise.
	(tfile_thread_alive, build_traceframe_info): Likewise.
	(tfile_traceframe_info, init_tfile_ops): Likewise.
	(_initialize_tracepoint): Don't call init_tfile_ops
	and add_target_with_completer.
	* tracefile-tfile.c: Include regcache.h, inferior.h, gdbthread.h,
	exec.h, completer.h and filenames.h.
	(_initialize_tracefile_tfile): New function.