Fix encoding of custom prepare extra data.

Patches:
	res_config_odbc-take2.patch by John Hardin (License #6512)
........

Merged revisions 413396 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@413397 f38db490-d61c-443f-a65b-d21fe96a405b