Update get_ilbc_source.sh script to work again.

Recently iLBC support in Asterisk has changed after the acquisition of GIPS
by Google. More information about how this may affect you is available in a
blog post at:

  http://blogs.asterisk.org/2011/09/19/ilbc-support-in-asterisk-after-googles-acquisition-of-gips/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@336572 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/scripts/get_ilbc_source.sh

@@ -22,7 +22,7 @@ read tmp
 
 wget -P codecs/ilbc http://www.ietf.org/rfc/rfc3951.txt
 
-wget -q -O - http://www.ilbcfreeware.org/documentation/extract-cfile.awk | tr -d '\r' > codecs/ilbc/extract-cfile.awk
+wget -q -O - http://www.ilbcfreeware.org/documentation/extract-cfile.txt | tr -d '\r' > codecs/ilbc/extract-cfile.awk
 
 (cd codecs/ilbc && awk -f extract-cfile.awk rfc3951.txt)