typo fix (s/TOTAG_LEN/TOTAG)

config.h

@@ -83,7 +83,7 @@
 #define RECEIVED_LEN 10
 
 #define TOTAG ";tag="
-#define TOTAG_LEN (sizeof(TOTAG_LEN)-1)
+#define TOTAG_LEN (sizeof(TOTAG)-1)
 
 #define SRV_PREFIX "_sip._udp."
 #define SRV_PREFIX_LEN 10