tcptls.h: Remove redundant SSL_CTX typedef.

It is invalid to typedef something more than once.  Though not all gcc
compilers on different OS's complain about it.

Change-Id: I5a7d4565990c985822d61ce75bde0b45f9870540

include/asterisk/tcptls.h

@@ -58,9 +58,6 @@
 #include "asterisk/netsock2.h"  /* for ast_sockaddr */
 #include "asterisk/utils.h"     /* for ast_flags */
 
-struct ssl_ctx_st;              /* forward declaration */
-typedef struct ssl_ctx_st SSL_CTX;
-
 /*! SSL support */
 #define AST_CERTFILE "asterisk.pem"