[fpc-pascal] Usage of TFPCustomImage

[Juha Manninen]

The class TFPCustomImage and its usage has apparently changed in FPC
3.0.2 (and trunk) compared to FPC 3.0.

This issue:
  https://bugs.freepascal.org/view.php?id=32005
is marked for TLazIntfImage (in LCL) but actually the problematic
procedure LoadFromStream is in TFPCustomImage.
Please read my note in the issue.

Question: how should TFPCustomImage be used now?
I guess TLazIntfImage must be changed accordingly.

Juha