CONTRIB: mod_defender: import the minimal number of includes

CONTRIB: mod_defender: import the minimal number of includes

mod_defender currently depends on haproxy includes while it should be
totally autonomous since it should build without and not even depend
on any specific haproxy version.

This imports the strictly minimum number of includes required to build
it. These have been manually stripped from their exported functions
prototypes and their unneeded dependencies.

In reality, the defender.c mostly needs sample.h because it stores its
data this way, spoe.h for the protocol definitions, and a few intops
and tools to decode varints. The rest mostly comes as intermediate
dependencies.