Remove obsolete w32-qt code
* configure.ac (w32-qt): Remove option and Qt checks. * src/Makefile.am: Remove BUILD_W32_QT handling. * src/kdpipeiodevice.cpp, src/kdpipeiodevice.h, src/kdpipeiodevice.moc, src/w32-qt-io.cpp: Removed.
This code was intended for Kleopatra but Kleopatra is not using
it anymore. QGpgme/dataprovider is a better replacement for this.