build: add support for optional pkg-config managed packages
build: add support for optional pkg-config managed packages

raphaelsc/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla,kjniemi/scylla,raphaelsc/scylla,duarten/scylla,duarten/scylla,kjniemi/scylla,scylladb/scylla,raphaelsc/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,kjniemi/scylla