Preparing for axTLS. Actual SSL API functions are only stubbed.

Added axTLS to autotool files and glue code to misc other files.
axtls.h maps SSL API functions, but may change.
axtls.c is just a stub file and will definitely change.

lib/sslgen.c

@@ -57,6 +57,7 @@
 #include "nssg.h"   /* NSS versions */
 #include "qssl.h"   /* QSOSSL versions */
 #include "polarssl.h" /* PolarSSL versions */
+#include "axtls.h"  /* axTLS versions */
 #include "sendf.h"
 #include "rawstr.h"
 #include "url.h"