[grsec] compilation error in latest patch

[Carlos Carvalho]

The latest version for 33.1 (201003201735.patch) doesn't compile:

net/ipv4/tcp_minisocks.c: In function ‘tcp_check_req’:
net/ipv4/tcp_minisocks.c:707: error: ‘grsec_enable_blackhole’ undeclared (first use in this function)

with

CONFIG_GRKERNSEC_RANDNET=y
# CONFIG_GRKERNSEC_BLACKHOLE is not set
# CONFIG_GRKERNSEC_SOCKET is not set

BTW, what functionality does blackhole offer that is not already
available via iptables and /proc tuning? From the config help I don't
see any.