* Updated "evhtp" restconf mode

* No reliance on libevent or libevhtp, but on libssl >= 1.1 directly
    * Moved out event handling to clixon event handling
    * Moved out all ssl calls to clixon
  * New code MUST use libevhtp from https://github.com/clixon/clixon-libevhtp.git
    * This does NOT work: libevhtp from https://github.com/criticalstack/libevhtp.git

lib/src/clixon_err.c

@@ -117,6 +117,7 @@ static struct errvec EV[] = {
     {"Routing demon error",    OE_ROUTING},
     {"XML error",              OE_XML},
     {"OpenSSL error",          OE_SSL},
+    {"RESTCONF error",         OE_RESTCONF},
     {"Plugins",                OE_PLUGIN},
     {"Yang error",             OE_YANG},
     {"FATAL",                  OE_FATAL},