BUG/MINOR: conf: "listener id" expects integer, but its not checked

The listener id was converted with a simple atol, so conversion
error are unchecked. This patch uses strtol and checks the
conversion status.
(cherry picked from commit e7fe8eb889b6e3a92892b0463ee6e61bebec0bb1)
(cherry picked from commit 0c5f31ba6e44878bf7b2ccb21736d39d8b9e51e8)
1 file changed