build qt_painter with -fno-rtti to fix link against QtMoko

QtMoko has all Qt built with -fno-rtti. If we build qt_painter with
rtti enabled it will compile fine but when attemting to run it, it
will print:

Error '/opt/qtmoko/lib/navit/graphics/libgraphics_qt_qpainter.so: undefined symbol: _ZTI11QMainWindow'