Fix minor issues with alarms code

This fixes up a couple of issues with alarms code I spotted:
* fakezmq.so didn't build due to not being able to find gmock/gmock.h - unlike other objects, modules/gmock/include wasn't in its include path. (I suspect most build machines are also set up to build Chronos - which requires that gmock/gtest be in the general system include-path - whereas my build machine is Sprout/Homestead-only at the moment, and needs the one under modules/.)
* AlarmQueueErrorTest.Overflow failed. Looking at the output, I spotted this:

```
Debug alarm.cpp:64: sprout issued 1001.3 alarm
Debug alarm.cpp:64: sprout issued 1001.3 alarm
Debug alarm.cpp:268: AlarmReqAgent: servicing request queue
Debug alarm.cpp:64: sprout issued 1001.3 alarm
Debug alarm.cpp:64: sprout issued 1001.3 alarm
```

which suggests that one alarm was getting taken off the queue, so when putting in AlarmReqAgent::MAX_Q_DEPTH+1 alarms, it never exceeded AlarmReqAgent::MAX_Q_DEPTH. I changed the test to put in AlarmReqAgent::MAX_Q_DEPTH+20 alarms, and it now passes consistently.