[fpc-pascal] modifying system.pp's InstallSignals

[Marco van de Voort]

In our previous episode, Seth Grover said:
> Does that seem like the right way for me to get the functionality of
> those calls available to me in InstallSignals? Or is there something
> easier I'm missing?

It is roughly ok. Optionally you can also -dFPC_USE_LIBC to force the system
unit to use libc instead of syscalls, and save a few kb. Note that this is
less frequently tested though.