[fpc-pascal] compiling 2.6.1 from 2.4.5

[Marco van de Voort]

In our previous episode, Thierry B. said:
> I come back to freepascal after one year and I wanted to build all 
> versions from my already installed 2.2.5. Builds:
> 
> - 2.4.0 from 2.2.5 : OK
> - 2.4.2 from 2.4.0 : OK
> - 2.4.4 from 2.4.2 : OK
> - 2.4.5 from 2.4.2 : OK
> - 2.6.1 from 2.4.5 : NOK : __missing_command_DATA2INC -b -s fppkg.cfg 
> fppkg.inc fppkg

This is usually a difference between a formal release and a badly installed
snapshot. Releases install data2inc, and the snapshot might not be fully
installed.