say: Fix a bug where SayNumber in Polish tries to play incorrect sound.

This change fixes a bug where calling SayNumber with a number divisible by
100 using the Polish language would cause the code to attempt to play a
sound file with an empty name.

(closes issue ASTERISK-23509)
Reported by: zvision

Review: https://reviewboard.asterisk.org/r/3378/
........

Merged revisions 411243 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@411244 65c4cc65-6c06-0410-ace0-fbb531ad65f3