Update symbols

Update symbols from amd64 build logs.

debian/libqtermwidget5-0.symbols

@@ -243,9 +243,7 @@ libqtermwidget5.so.0 libqtermwidget5-0 #MINVER#
  (c++)"vtable for Konsole::UrlFilter@Base" 0.15.0
  (c++)"QTermWidget::~QTermWidget()@Base" 0.6.0
  (c++)"QTermWidget::setBoldIntense(bool)@Base" 0.15.0+git20200620
- (c++)"std::__cxx11::_List_base<QByteArray, std::allocator<QByteArray> >::_M_clear()@Base" 0.15.0+git20200620
  (c++)"non-virtual thunk to QTermWidget::~QTermWidget()@Base" 0.6.0
  (c++)"typeinfo for QTermWidget@Base" 0.6.0
  (c++)"typeinfo name for QTermWidget@Base" 0.6.0
- (optional|c++)"void std::__cxx11::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::_M_construct<wchar_t const*>(wchar_t const*, wchar_t const*, std::forward_iterator_tag)@Base" 0.9.0~
  (c++)"vtable for QTermWidget@Base" 0.6.0