Bug#1038693: qt6-declarative-dev: inappropriately included cmake file

[Oswald Buddenhagen]

cmake files are necessary for static builds, because the "plugins" 
aren't actually plugins then. at least i'm assuming that this 
functionality wasn't lost during the cmake port ...

plugins may also be listed as runtime dependencies for deployment.  
theoretically - whether that was actually implemented, i don't know.

neither of these are immediately relevant for a regular desktop build, 
but you shouldn't be surprised when applications fail to build due to 
formally missing dependencies.