Fixed compiling warnings around ASSERTs doing pointer math

stuncore/stunbuilder.cpp

@@ -568,7 +568,7 @@ HRESULT CStunMessageBuilder::AddMessageIntegrityLongTerm(const char* pszUserName
     pDst += lenPassword;
     *pDst ='\0'; // null terminate for debugging (this char doesn not get hashed
     
-    ASSERT((pDst-key) == lenTotal);
+    ASSERT(key+lenTotal == pDst);
 
 #ifndef __APPLE__
     pResult = MD5(key, lenTotal, hash);

stuncore/stunreader.cpp

@@ -342,7 +342,7 @@ HRESULT CStunMessageReader::ValidateMessageIntegrityLong(const char* pszUser, co
     }
     *pDst = '0'; // null terminate for debugging (does not get hashed)
     
-    ASSERT((pDst-key) == totallength);
+    ASSERT(key+totallength == pDst);
     
 #ifndef __APPLE__
     ChkIfA(NULL == MD5(key, totallength, hash), E_FAIL);