As noted in #28709 OpenWrt contains CONFIG_
symbols for Zabbix even when no Zabbix package is selected.
This fixes and Closes#28709.
We add a 'guard' symbol for the menus and choices so the only
generate CONFIG symbols when 'Enable Zabbix'
(CONFIG_ZABBIX_ENABLE_ZABBIX) is selected.
We also make all the Zabbix packages depend on this symbol,
for consistency.
This operates much as the pseudo-package solution, but without
a pseudo-package required.
Signed-off-by: Daniel F. Dickinson <dfdpublic@wildtechgarden.ca>
f0576eb36b