Some module .pri files unexpectedly do not have corresponding prl files.

Qt 6 as distributed by the installer appears to be missing prl files for the following modules (which are not marked as library-less via "no_link" in their respective module .pri file):

• libQt6Linguist
• libQt6Tools
• libQt6UiPlugin

(Note that only the latter one exists for Qt 5.15, and does not have its own library, but only lists dependencies in its prl file.)

In addition, now mkspecs/modules has .pri files for all the plugins, which formerly existed only for static builds. Is this intended? If so, is the intention now that consuming code should assume the presence of prl files only for static builds in the case of qt_plugin_*.pri?