(play): Continue after input read error, treating it like EOF. This

fixes error handling when a script can be opened but not read: it
switches back to standard input.  And it handles errors on standard
input more gracefully: orderly shutdown, buffered output is still
written out.

src/client/play.c

@@ -271,7 +271,7 @@ play(int sock)
 	    n = recv_input(input_fd, &inbuf);
 	    if (n < 0) {
 		perror("read stdin"); /* FIXME stdin misleading, could be execing */
-		return -1;
+		n = 0;
 	    }
 	    if (n == 0) {
 		/* EOF on input */