Add '-coreid' target option to support multiple cores per TAP.

ARM Cortex-A9 multi-core chips expose a single TAP/DAP which connects
to both cores.  The '-coreid' option selects which core the target
should connect to.

Note that at present, OpenOCD can connect to either core, but not both
simulatenously, until ADI contexts can be shared.

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>

src/target/target.h

@@ -107,6 +107,7 @@ struct target
 	const char *cmd_name;				/* tcl Name of target */
 	int target_number;					/* DO NOT USE!  field to be removed in 2010 */
 	struct jtag_tap *tap;					/* where on the jtag chain is this */
+	int coreid;							/* which device on the TAP? */
 	const char *variant;				/* what variant of this chip is it? */
 
 	/**