Add qgpgme as qt language binding
* configure.ac: Add version defines. Check for qt if neccessary. * lang/README: Mention qt * lang/cpp/src/GpgmeppConfig.cmake.in.in: Remove comment. Find qgpgme. * lang/qt/src/Makefile.am: New. Build qgpgme. * lang/qt/README, lang/qt/src/Makefile.am, lang/qt/src/QGpgmeConfig.cmake.in.in, lang/qt/src/QGpgmeConfigVersion.cmake.in, lang/qt/src/dataprovider.cpp, lang/qt/src/dataprovider.h, lang/qt/src/qgpgme_export.h, m4/qt.m4: New. * lang/cpp/src/GpgmeppConfig.cmake.in.in, lang/cpp/src/Makefile.am: Fix generated config file.
For now this is just the dataprovider which was part of the
KF5 Gpgmepp QGpgme variant. This is very thin but a useful
class which is used downstream.