(legacy) fix PHP Fatal error:  Call to undefined function lock() in /usr/local/etc/inc/system.inc on line 125

traceback missing library issue, search function where lock() is used in line 125 (system_resolvconf_generate), then check use and add
missing library,

grep -r system_resolvconf_generate * | sed 's/:/ /g' | awk '{print $1;}' | sort -u