stasis: Made internal_stasis_subscribe() prototype and definition match exactly.
........

Merged revisions 409682 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@409683 f38db490-d61c-443f-a65b-d21fe96a405b