www/geolizer: fix build with GCC-based architectures

Add USES=compiler:c++11-lang to www/webalizer when using GEOIP option:
/usr/local/include/maxminddb.h:92: error: expected '=', ',', ';', 'asm' or 'attribute' before 'mmdb_uint128_t'
/usr/local/include/maxminddb.h:122: error: expected specifier-qualifier-list before 'mmdb_uint128_t'

Approved by: mentors (implicit approval)