Octave compilation slowed due to errors in interpreter

[Daniel J Sebald]

The latest developer branch tip creates a lot of errors like this

../../run-octave -f -q -H -p ../../../octave/doc/interpreter --eval 
"sparseimages ('gplot', 'png');"
**
GLib-GIO:ERROR:gdbusconnection.c:2270:initable_init: assertion failed: 
(connection->initialization_error == NULL)
octave exited with signal 6

when compiled and slows down compilation to something much longer than 
it used to be for the most simple of mods in, say, the GUI directory. 
There seems to be about one dozen such errors.  Since these fail, it 
seems the commands are run every time Octave is compiled.

Dan