Added ASN debug group to log low-level encoding/decoding (ASN.1, X.509).

This will allow us to remove quite some clutter from the LIB debug group
for higher debug levels.

src/libstrongswan/debug.h

@@ -48,6 +48,8 @@ enum debug_t {
 	DBG_KNL,
 	/** networking/sockets */
 	DBG_NET,
+	/** low-level encoding/decoding (ASN.1, X.509 etc.) */
+	DBG_ASN,
 	/** message encoding/decoding */
 	DBG_ENC,
 	/** trusted network connect */