make-ngram-pfsg: bad results with new gawk version

[Matthias Thomae]

Andreas Stolcke wrote:
> Thanks for tracking this down.

You're welcome.

>  I'll add a note somewhere that one better
> set LC_NUMERIC=C or LC_ALL=C for gawk scripts to do proper artihmetic.

Good. Maybe you would even want to set LC_NUMERIC temporarily (from a 
wrapper script?) or print a warning if it is not set to "C".

Regards.
Matthias