Add RPORT to the list of DCERPC ports to check

[FixRM #8479]
Just use a straight RPORT, don't sneak 593.

Incidentally, the endmap scanner doesn't appear to work at all for
http-rpc-epmap, so no harm done anyway (tested against Windows 2008
server).

It looks like a bigger change than it realy is, thanks to the indentaton
changes by removing the itertor. Diff this without whitespace changes to
get a better idea of what's actually different.
Land #2507, @todb-r7's fix to allow DCERPC misin to use RPORT