Fix from review

Author: embhorn

src/tls.c

@@ -14783,9 +14783,10 @@ static int TLSX_GetSize(TLSX* list, byte* semaphore, byte msgType,
      *     &cbShim); length += cbShim;`
      */
     word32 length = 0;
-    word16 cbShim;
+    word16 cbShim = 0;
     byte   isRequest = (msgType == client_hello ||
                         msgType == certificate_request);
+    (void)cbShim;
 
     while ((extension = list)) {
         list = extension->next;