I have pretty same list of errors on builded client startup as you have. And only these lines are the extra ones comparing to the official client startup error list:
crystalspace.maploader:
Could not find mesh factory ‘mesh_example’.
planeshift_effects:
Couldn't find mesh factory mesh_example in effect mesh_example
Problem with an effect obj in: mesh/x_obj_mesh
crystalspace.maploader:
Could not find mesh factory ‘mesh_example’.
planeshift_effects:
Couldn't find mesh factory mesh_example in effect mesh_example2
Problem with an effect obj in: mesh/x_obj_mesh
Don't know, does it affect something at run-time or not...
I've also noticed a configuration warning about missing 'libjpeg8-dev' in your logs. Debian 8 does not have this package, indeed. I've pushed update to 'ps-prereq-jessie.sh', replacing 'libjpeg8-dev' with 'libjpeg-dev'.