semihosting: add semihosting_basedir command

This command allows users to set base working directory for the
semihosting I/O operations.Default is the current OpenOCD directory.

Signed-off-by: Erhan Kurubas <erhan.kurubas@espressif.com>
Change-Id: I80c5979e4c96d66cccdd12cc6fcd5f353e5c6b4d
Reviewed-on: https://review.openocd.org/c/openocd/+/6888
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/semihosting_common.h

@@ -176,6 +176,9 @@ struct semihosting {
 	/** The current time when 'execution starts' */
 	clock_t setup_time;
 
+	/** Base directory for semihosting I/O operations. */
+	char *basedir;
+
 	int (*setup)(struct target *target, int enable);
 	int (*post_result)(struct target *target);
 };