Comment 1 for bug 1487267

Not too familiar with buildconf, but it looks like you are just creating a library from the plugin files.. I think qMake (or cmake) add metadata to the plugin library that is currently missing. Should explain the error that I receive

plugin cannot be loaded for module "QLightDM": Plugin verification data mismatch in '/usr/local/lib/qt5/qml/QLightDM/libQLightDM.so'

I can't find anyone who has built a qt5 plugin with buildconf however...