* plug-ins/libgimpoldpreview/*: removed.

* plug-ins/Makefile.am
* plug-ins/common/Makefile.am: changed accordingly.

* plug-ins/common/max_rgb.c
* plug-ins/common/noisify.c
* plug-ins/common/tileit.c: removed last forgotten
  #include "libgimpoldpreview.h".