Fix gif interface _routerv6 files not being created. Fixes #11545
Fix gif interface _routerv6 files not being created. Fixes #11545

interface_gif_configure() uses the global variable $g to look up the temp
directory in which to write the router/gateway files used for gateway
monitoring. The declaration of $g in this scope was inadvertently removed in
revision fee94b6fe34. This commit restores the declaration.

pfsense/pfsense,pfsense/pfsense,pfsense/pfsense,pfsense/pfsense