Comment # 4 on bug 1218288 from Shawn Dunn

https://build.opensuse.org/request/show/1138375

This should fix the issue.   There's not really a good reason to not have a
hard require to make sure both are installed, due to the construction of this
package.

At worst case, forcing the installation of liblxqt in all cases adds the grand
total of 14.8KB of disk space.