tweaks: avoid an unused-variable warning for the tiny version

The extra variable is not needed, because when having read from
standard input, the filename will simply be empty.  It will not
be empty for any other file that was read.

src/nano.c

@@ -2534,7 +2534,6 @@ int main(int argc, char **argv)
     /* Read the files mentioned on the command line into new buffers. */
     while (optind < argc && (!openfile || ISSET(MULTIBUFFER))) {
 	ssize_t givenline = 0, givencol = 0;
-	bool dash = FALSE;
 
 	/* If there's a +LINE[,COLUMN] argument here, eat it up. */
 	if (optind < argc - 1 && argv[optind][0] == '+') {
@@ -2547,7 +2546,6 @@ int main(int argc, char **argv)
 	if (strcmp(argv[optind], "-") == 0) {
 	    if (!scoop_stdin())
 		continue;
-	    dash = TRUE;
 	    optind++;
 	} else if (!open_buffer(argv[optind++], FALSE))
 	    continue;
@@ -2556,7 +2554,7 @@ int main(int argc, char **argv)
 	if (givenline != 0 || givencol != 0)
 	    do_gotolinecolumn(givenline, givencol, FALSE, FALSE);
 #ifndef DISABLE_HISTORIES
-	else if (ISSET(POS_HISTORY) && !dash) {
+	else if (ISSET(POS_HISTORY) && openfile->filename[0] != '\0') {
 	    ssize_t savedline, savedcol;
 	    /* If edited before, restore the last cursor position. */
 	    if (has_old_position(argv[optind - 1], &savedline, &savedcol))