[Pkg-kde-extras] Bug#927991: Fix for FTBFS

[Gregor Riepl]

Dear maintainer,

With the latest upload of MariaDB 10.3, --libmysqld-libs is now supported by
mysql_config/mariadb_config:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=928230#46

Can you please trigger a rebuild of amarok once mariadb-10.3_1:10.3.15-1 has
hit unstable?

Please also consider unblocking the package so it can still go back into
buster, if possible.

Thanks!