replace security/stegcracker with security/stegseek

Hi,
not long ago, stegcracker was imported. I saw an update is available, looking at it,
it says, that's the last version, use stegseek, as that's "lightning fast". Which indeed, it
is. So attached a port of stegseek.

so, I'd like to get rid of security/stegcracker, and add security/stegseek.
Works for me on amd64. The patch helps to make it build, don't know if that
would break on non 64bit archs?

for the quirks, just use reason 3: "no longer maintained upstream"
or add a new one: "no longer maintained upstream, suggest stegseek" ?

cheers,
Sebastian