allow zero length padding

libi2pd/SSU2Session.cpp

@@ -2477,14 +2477,9 @@ namespace transport
 		size_t paddingSize = rand () & 0x0F; // 0 - 15
 		if (paddingSize + 3 > len) paddingSize = len - 3;
 		else if (paddingSize + 3 < minSize) paddingSize = minSize - 3;
-		if (paddingSize)
-		{
 		buf[0] = eSSU2BlkPadding;
 		htobe16buf (buf + 1, paddingSize);
 		memset (buf + 3, 0, paddingSize);
-		}
-		else
-			return 0;
 		return paddingSize + 3;
 	}