src/jtag: remove 'extern' and wrap headers.

Removes the 'extern' keyword from function declarations.
Wraps long prototypes to fit into 80 columns.

Fixes documentation for jtag_tap_s::{,has}idcode fields.

src/jtag/bitq.h

@@ -50,8 +50,8 @@ typedef struct bitq_state_s
 
 extern bitq_interface_t *bitq_interface;
 
-extern int bitq_execute_queue(void);
+int bitq_execute_queue(void);
 
-extern void bitq_cleanup(void);
+void bitq_cleanup(void);
 
 #endif /* BITQ_H */