ft_render runtime errors

[Mike Miller]

Michael, all,

I recently updated the hydra continuous build of Octave to link in the
libraries needed for native graphics support. It did not previously
have libGL or Fontconfig or FreeType as build dependencies. This has
now made the build start failing in the doc/interpreter directory when
it runs the plot scripts to build the manual. See the latest build log
[1] for the error, excerpted here:

../../run-octave -f -q -H -p . --eval "geometryimages ('voronoi', 'eps');"
warning: X11 DISPLAY environment variable not set
Fontconfig warning: line 26: empty font directory name ignored
warning: could not match any font: *-normal-normal-10
warning: ft_render: unable to load appropriate font
[snipped hundreds of identical lines]
warning: ft_render: invalid bounding box, cannot render
error: legend: A(I): index out of bounds; value 3 out of bound 0
error: called from:
error:   .../legend.m at line 622, column 22
error:   .../geometryimages.m at line 54, column 5

In addition, the i386 build aborts now when running the graphics.cc
tests, with a glibc memory error "free(): invalid next size (fast):
0x09e29da0" [2] after displaying the same Fontconfig warning as above.

I originally saw an error about a missing Fontconfig file, so I added
FONTCONFIG_FILE to the build environment, but that didn't help much.
Hydra's build environment definitely has its fair share of quirks.
This may still be a misconfigured Fontconfig environment but I don't
know what else to try to get this working. Any suggestions or
possibilities that this could be an error in Octave? Has Octave been
tested with a broken Fontconfig configuration?

[1] http://hydra.nixos.org/build/5916103/log
[2] http://hydra.nixos.org/build/5916106/log

Thanks,

-- 
mike