timestamps changed from uint64_t to int64_t

There were cases in the code where time calculations and comparisons were overflowing and causing connection instability.  This will keep time calculations within expected ranges.

osdep/PortMapper.cpp

@@ -131,7 +131,7 @@ public:
 
 					InetAddress publicAddress;
 					sendpublicaddressrequest(&natpmp);
-					uint64_t myTimeout = OSUtils::now() + 5000;
+					int64_t myTimeout = OSUtils::now() + 5000;
 					do {
 						fd_set fds;
 						struct timeval timeout;