MFH: r544732

x11-themes/qtcurve: fix build on GCC architectures

Merge upstream patch to fix build:
/wrkdirs/usr/ports/x11-themes/qtcurve-gtk2/work/qtcurve-1.9/.cmake_utils_base/cmake_c_macros/include_fix/qtcurve-utils/gtkprops.h: In member function 'constexpr GObject* QtCurve::GtkWidgetProps::Props::_SigConn_tabChildAdd_ObjGetter::operator()(QtCurve::GtkWidgetProps::Props::SigConn<QtCurve::GtkWidgetProps::Props::_SigConn_tabChildAdd_ObjGetter>*) const':
/wrkdirs/usr/ports/x11-themes/qtcurve-gtk2/work/qtcurve-1.9/.cmake_utils_base/cmake_c_macros/include_fix/qtcurve-utils/gtkprops.h:80:24: error: a reinterpret_cast is not a constant expression

80 |                 return (GObject*)qtcContainerOf(p, Props, name)->m_w;   \
   |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Approved by: portmgr (fix build blanket)