Do you use GNU Motion w/ webcam for remote monitoring?

I’m having a dickens of a time getting past the config stage.

Here’s what I’ve done :
In the ffmpeg source folder,
./configure/ffmpeg-0.4.9-pre1 –enable-shared

In the GNU Motion source folder :
./configure

the configuration fails at :

checking size of short int… configure: error: cannot computer sizeof (short int), 77

Is there something I missed to make sure that Motion sees the ffmpeg libraries?