Just get RTS libs from it's package conf

rts.conf already contains this exact information in its extra-libraries stanza.

I am not sure whether deleting this stuff will work right out of the gate, but I think this ultimately the correct approach.

CC @alp @angerman @bgamari

• are either individually buildable or squashed
• have commit messages which describe what they do (referring to Notes and tickets using #NNNN syntax when appropriate)
• have added source comments describing your change. For larger changes you likely should add a Note and cross-reference it from the relevant places.
• add a testcase to the testsuite.
• replace this message with a description motivating your change

If you have any questions don't hesitate to open your merge request and inquire in a comment. If your patch isn't quite done yet please do add prefix your MR title with WIP:.