[fpc-pascal] old code with readdir

[mondrillo]

Error: Identifier not found "opendir"

Hello list, 

I have old code from freepascal older than 2.0.0, and I want to migrate
to amd64 debian, but have this error, I have read in googlin about this
problem but the possible solutions, use oldlinux ( not avaliable with
this version o freepascal) or baseunix this resolv some of problems but
not at all.
 Error: Identifier not found "pdir"
 Error: Error in type definition
 Error: Identifier not found "pdirent"
 Error: Error in type definition
 (this resolved with baseunix unit) 
 Error: Identifier not found "opendir"
 Error: Operator is not overloaded

Thank's and regards