gengetopt not listed in dependencies

[robn]

make[1]: Entering directory '/home/robn/code/libu2f-server/src'
gengetopt --no-handle-help --input cmdline.ggo Makefile.am
/bin/bash: gengetopt: command not found
Makefile:790: recipe for target 'cmdline.c' failed
make[1]: *** [cmdline.c] Error 127
make[1]: Leaving directory '/home/robn/code/libu2f-server/src'

Easily fixed via apt-get install gengetopt, but it should probably be listed in the docs.