jtag: make cmd_queue_scan_field_clone public

This patch makes the cmd_queue_scan_field_clone function public. This
permits targets to insert fields without affecting the submitted
scan_field list. This will be used in an upcoming target implementation
that needs to insert additional padding bits.

Change-Id: I8fbd3b9b4e413432471f4f1444048932c8fa189e
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/4082
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

src/jtag/commands.h

@@ -168,6 +168,7 @@ void *cmd_queue_alloc(size_t size);
 void jtag_queue_command(struct jtag_command *cmd);
 void jtag_command_queue_reset(void);
 
+void jtag_scan_field_clone(struct scan_field *dst, const struct scan_field *src);
 enum scan_type jtag_scan_type(const struct scan_command *cmd);
 int jtag_scan_size(const struct scan_command *cmd);
 int jtag_read_buffer(uint8_t *buffer, const struct scan_command *cmd);