[GD 2.1.0] enabling functions or not when a dep is missing

Dear list,

While wokring on the issue #131
(http://bugs.libgd.org/?do=details&task_id=131 c++ binding), we come
to a point to choose whether we should expose the API when the feature
is actually not available. For example, expose the JPEG functions when
the libjpeg is not available. The XPM functions do it already (and it
is the only one) and outputs an error message to stderr when called.

We choosed to do it for the c++ binding as it makes the developers
life easier (no need to recompile an application).


What do you think about doing the same for the standard C functions?
We can even add a return code instead of simply raising an error in
stderr.

Opinions, suggestions and comments welcome!

-- 
Pierre
http://blog.thepimp.net | http://www.libgd.org