BUG/MINOR: quic: check applet_putchk() for 'show quic' first line

Ensure applet_putchk() return value is checked when outputing via the
CLI 'show quic' header line.

This is only to align with other usages of the same function, as trash
output buffer should always be large enough for it. As such, the command
is simply aborted if this is not the case.

This should fix coverity report from github issue #3139.

This could be backported up to 2.8.

src/quic_cli.c

@@ -460,7 +460,10 @@ static int cli_io_handler_dump_quic(struct appctx *appctx)
 				      "in_flight infl_p lost_p         "
 				      "Local Address           Foreign Address      "
 				      "local & remote CIDs\n");
-			applet_putchk(appctx, &trash);
+			if (applet_putchk(appctx, &trash) == -1) {
+				/* Trash buf too short without any data emitted yet, should never happen. */
+				goto done;
+			}
 		}
 	}