Fix chan_jingle/gtalk load regression introduced in r346087

Fix chan_jingle/gtalk load regression introduced in r346087

Add missing symbol exports for ast_aji_client_destroy and ast_aji_buddy_destroy
for usage outside res_jabber.  Testing of these changes focused on res_jabber
itself, so this problem was missed.

Reported-by: Michael Spiceland
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Merged revisions 346951 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 346952 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@346953 65c4cc65-6c06-0410-ace0-fbb531ad65f3