Prevent double uri_escaping in chan_sip when pedantic is enabled

Prevent double uri_escaping in chan_sip when pedantic is enabled

If pedantic mode is enabled, outbound invites will have double-escaped
contacts.  This avoids setting an already-escaped string into a field
where it is expected to be unescaped.

(closes issue ASTERISK-20023)
Reported by: Walter Doekes
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Merged revisions 369993 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 369994 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369995 65c4cc65-6c06-0410-ace0-fbb531ad65f3