tweaks: only compensate for a partially-offscreen line in softwrap mode

A line can only be partially offscreen when doing softwrapping.

src/winio.c

@@ -2949,12 +2949,14 @@ void edit_scroll(scroll_dir direction, int nrows)
 	go_forward_chunks(editwinrows - nrows, &line, &leftedge);
 
 #ifndef NANO_TINY
+    if (ISSET(SOFTWRAP)) {
 	/* Compensate for the earlier chunks of a softwrapped line. */
 	nrows += chunk_for(leftedge, line);
 
 	/* Don't compensate for the chunks that are offscreen. */
 	if (line == openfile->edittop)
 	    nrows -= chunk_for(openfile->firstcolumn, line);
+    }
 #endif
 
     /* Draw new content on the blank rows inside the scrolled region