Not all versions of gnu-linux use glibc, which contains iconv. Some...

Not all versions of gnu-linux use glibc, which contains iconv.  Some (especially embedded systems) don't have iconv at all.
(closes issue #15169)
 Reported by: pprindeville


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@214152 65c4cc65-6c06-0410-ace0-fbb531ad65f3