Merge bitcoin/bitcoin#35978: contrib/init: fix unused variables in openrc script

d837bb38a4 contrib/init: fix unused variables in openrc script (jpk68)

Pull request description:

  - Makes it so that `${BITCOIND_BIN}` is actually used as `command=`, rather than the hardcoded `/usr/bin/bitcoind`.
  - Passes `BITCOIND_GROUP` to `start-stop-daemon`, so that the daemon process itself runs under it.

ACKs for top commit:
  jeanpablojp:
    utACK d837bb38a4
  thomasbuilds:
    ACK d837bb38
  winterrdog:
    utACK d837bb38a4

Tree-SHA512: 78c237224d65cc47ade606df4808fbf4ca70109d95301c35d1b336eead1b25138a83ce6f2314775b8a11a6745af2220af9027640530b9edb7e0167ccea081b6b

contrib/init/bitcoind.openrc

@@ -21,7 +21,7 @@ BITCOIND_OPTS="${BITCOIND_OPTS:-${BITCOIN_OPTS}}"
 name="Bitcoin Core Daemon"
 description="Bitcoin cryptocurrency P2P network daemon"
 
-command="/usr/bin/bitcoind"
+command="${BITCOIND_BIN}"
 command_args="-pid=\"${BITCOIND_PIDFILE}\" \
 		-conf=\"${BITCOIND_CONFIGFILE}\" \
 		-datadir=\"${BITCOIND_DATADIR}\" \
@@ -30,6 +30,7 @@ command_args="-pid=\"${BITCOIND_PIDFILE}\" \
 
 required_files="${BITCOIND_CONFIGFILE}"
 start_stop_daemon_args="-u ${BITCOIND_USER} \
+			-g ${BITCOIND_GROUP} \
 			-N ${BITCOIND_NICE} -w 2000"
 pidfile="${BITCOIND_PIDFILE}"