Fix plataform info for qt
Update pkg-config to Qt5* libs
Migrate to qt5 (includes QtGui -> QtWidgets, toAscii -> toLatin, QApplication::GuiClient from QApplication() in main)
Use wxString::utf8_str() to avoid ambiguity as Qt5 now expect that encoding for QString::QString(const char * str)
Add QT_WIDGETS_LIB define to enable QWidget* support in QTest (needed by uiactionsim)
add SAMPLES_CXXFLAGS option for -fPIC due Qt is built with -reduce-relocations