Remove a superfluous and dangerous freeing of an SSL_CTX.

Remove a superfluous and dangerous freeing of an SSL_CTX.

The problem here is that multiple server sessions share
a SSL_CTX. When one session ended, the SSL_CTX would be
freed and set NULL, leaving the other sessions unable to
function.

The code being removed is superfluous because the SSL_CTX
structures for servers will be properly freed when ast_ssl_teardown
is called.

(closes issue ASTERISK-20074)
Reported by Trevor Helmsley
Patches:
	ASTERISK-20074.diff uploaded by Mark Michelson (license #5049)
Testers:
	Trevor Helmsley
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Merged revisions 369731 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 369732 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369733 65c4cc65-6c06-0410-ace0-fbb531ad65f3