Add complete JTAG debug logging.

Add complete JTAG debug logging.

Sample output, with default_interface_jtag_execute_queue replaced by
dijeq to satisfy commit message line length check:
Debug: 646 18 core.c:847 dijeq(): JTAG IR SCAN to RUN/IDLE
Debug: 647 18 core.c:852 dijeq():   5b out: 11
Debug: 648 18 core.c:847 dijeq(): JTAG DR SCAN to RUN/IDLE
Debug: 649 18 core.c:852 dijeq():   40b out: 4400000001
Debug: 650 18 core.c:857 dijeq():   40b in: 4400000000

Signed-off-by: Tim Newsome <tim@sifive.com>
Change-Id: I014e9e3a77755413b36edfcede2ab8f6aa08061b
Reviewed-on: http://openocd.zylin.com/4451
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>