As clandmeter mentioned in a ticket (https://github.com/libcheck/check/issues/138) for that project setting the switch —disable-forks was needed to conform to the grsec kernel.
Now that this grsec/hardened kernel is gone. This change could be reverted at some time.
At least one possible new package (testing/burp) depends on that setting.

(from redmine: issue id 8538, created on 2018-02-21)