startup: in default mode, display the tail of the file as Pico does

When not using --smooth (nor 'set smooth'), and a line near or beyond
the end-of-file is addressed with the + command-line argument, then
center the cursor, just like Pico does -- so in the default mode,
nano is again more like Pico.

This partially addresses https://savannah.gnu.org/bugs/?51489.

src/search.c

@@ -912,7 +912,7 @@ void do_gotolinecolumn(ssize_t line, ssize_t column, bool use_answer,
 	/* If the target line is close to the tail of the file, put the last
 	 * line or chunk on the bottom line of the screen; otherwise, just
 	 * center the target line. */
-	if (rows_from_tail < editwinrows / 2) {
+	if (rows_from_tail < editwinrows / 2 && ISSET(SMOOTH_SCROLL)) {
 	    openfile->current_y = editwinrows - 1 - rows_from_tail;
 	    adjust_viewport(STATIONARY);
 	} else