Added "--discard" option.

src/include/options.h

@@ -45,6 +45,7 @@ struct opts_s {           /* structure describing run-time options */
 	bool stop_at_size;             /* set if we stop at "size" bytes */
 	bool sync_after_write;         /* set if we sync after every write */
 	bool direct_io;                /* set if O_DIRECT is to be used */
+	bool discard_input;            /* set to write nothing to stdout */
 	double interval;               /* interval between updates */
 	double delay_start;            /* delay before first display */
 	unsigned int watch_pid;	       /* process to watch fds of */

src/include/pv-internal.h

@@ -97,6 +97,7 @@ struct pvstate_s {
 	bool direct_io;                  /* set if O_DIRECT is to be used */
 	bool direct_io_changed;          /* set when direct_io is changed */
 	bool no_splice;                  /* never use splice() */
+	bool discard_input;              /* write nothing to stdout */
 	unsigned long long rate_limit;   /* rate limit, in bytes per second */
 	unsigned long long target_buffer_size;  /* buffer size (0=default) */
 	unsigned long long size;         /* total size of data */

src/include/pv.h

@@ -116,6 +116,7 @@ extern void pv_state_direct_io_set(pvstate_t, bool);
 extern void pv_state_rate_limit_set(pvstate_t, unsigned long long);
 extern void pv_state_target_buffer_size_set(pvstate_t, unsigned long long);
 extern void pv_state_no_splice_set(pvstate_t, bool);
+extern void pv_state_discard_input_set(pvstate_t, bool);
 extern void pv_state_size_set(pvstate_t, unsigned long long);
 extern void pv_state_interval_set(pvstate_t, double);
 extern void pv_state_width_set(pvstate_t, unsigned int);