build: add configure-time check for gnutls-devel
build: add configure-time check for gnutls-devel

cloudius-systems/seastar,syuu1228/seastar,dreamsxin/seastar,dreamsxin/seastar,kjniemi/seastar,cloudius-systems/seastar,scylladb/seastar,kjniemi/seastar,syuu1228/seastar,syuu1228/seastar,avikivity/seastar,scylladb/seastar,sjperkins/seastar,cloudius-systems/seastar,dreamsxin/seastar,sjperkins/seastar,avikivity/seastar,sjperkins/seastar,kjniemi/seastar,avikivity/seastar,scylladb/seastar