xapian-core: update to 1.4.19
xapian-core: update to 1.4.19

* Add pgp key to verify source tarball.
* Install license file.
fabiangreffrath/MINGW-packages,lhmouse/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,oroppas/MINGW-packages,oroppas/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,fabiangreffrath/MINGW-packages,oscarfv/MINGW-packages,Alexpux/MINGW-packages,JPeterMugaas/MINGW-packages,Alexpux/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,Alexpux/MINGW-packages,JPeterMugaas/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages,oroppas/MINGW-packages,lhmouse/MINGW-packages,Alexpux/MINGW-packages,JPeterMugaas/MINGW-packages,oscarfv/MINGW-packages,oroppas/MINGW-packages,lhmouse/MINGW-packages,fabiangreffrath/MINGW-packages,fabiangreffrath/MINGW-packages,stahta01/MINGW-packages,Alexpux/MINGW-packages,fabiangreffrath/MINGW-packages,oroppas/MINGW-packages,JPeterMugaas/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,oroppas/MINGW-packages,Alexpux/MINGW-packages,fabiangreffrath/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages