Fix memory leaks

[peter-esik]

Even though these leaks are pretty small, when using "branching mode", the one in IsInLeft accumulates quickly over time. For example, running the tool over the weekend resulted in 80+ GBs of allocated memory in my case.

On e.g. macOS, the presence of memory leaks can be checked easily: export MallocStackLogging=1;leaks --atExit -- p4-fusion [parameters];unset MallocStackLogging