Remove double-free when SSL is used.

Two PRs, #143 and #99, close a memory leak by freeing evhtp_t.ssl_ctx.
Since they modify the same function at different points within the
function, the memory is freed twice. This patch removes the second call
to SSL_CTX_free().

Releases are affected as follows:
before 1.2.7: evhtp_t.ssl_ctx is leaked
1.2.7 through 1.2.9: OK
1.2.10 and 1.2.11: evhtp_t.ssl_ctx is freed twice

evhtp.c

@@ -4250,7 +4250,7 @@ evhtp_free(evhtp_t * evhtp) {
 
 #ifndef EVHTP_DISABLE_SSL
     if (evhtp->ssl_ctx) {
-        SSL_CTX_free(evhtp->ssl_ctx);
+        evhtp_safe_free(evhtp->ssl_ctx, SSL_CTX_free);
     }
 #endif
 
@@ -4271,12 +4271,6 @@ evhtp_free(evhtp_t * evhtp) {
         evhtp_safe_free(evhtp_alias, free);
     }
 
-#ifndef EVHTP_DISABLE_SSL
-    if (evhtp->ssl_ctx) {
-        SSL_CTX_free(evhtp->ssl_ctx);
-    }
-#endif
-
     evhtp_safe_free(evhtp, free);
 } /* evhtp_free */