fix BufferPane::screen_rows_below_line() while loop

src/gui/BufferPane.cc

@@ -81,7 +81,7 @@ int BufferPane::screen_rows_below_line(const Buffer::Iterator & line)
 {
     Buffer::Iterator i = line;
     int rows = 0;
-    while ((rows < m_rows) && i.go_next_line());
+    while ((rows < m_rows) && i.go_next_line())
     {
         rows += rows_in_line(i);
     }