[fpc-pascal] installing cross fpc in parallel to systems fpc

[Marco van de Voort]

In our previous episode, Marc Santhoff said:
> > #ENDIF
> 
> I see, so when using fpc for ARM these define is automatically set?
> And would that be CPUAVR for Atmels chips?

(easiest is to just fpc -va some dummy source and then grep for CPU, or look
in the compiler sources (options.pas or systems/ iirc)

You can select a different cpu then the default using fpc -P<architecture>

So if you have a x86 compiled fpc.exe, you can get it to select ppcx64 using
fpc -Px86_64 and then e.g. -Twin64 for the target.  Then all the relevant
directives (CPU64, cpux86_64, win64, mswindows etc) are defined.

(I use windows now because I know those defines by heart, for arm it is the
same).

The buildfaq (document section on the FPC site), though somewhat outdated,
has some info and examples on this.