assignments/mini-libc: Proper synchronization of tests and targets in memory-measuring tests

[razvand]

The implementation of memory-measuring tests relies on sleeps both in the target program and in the test itself. This is imperfect and may be the cause of synchronization issues.

A better implementation, that makes the test interact with the target, is required. The implementation would wait for input to be provided by the target, do required operations, send input to the target to "unlock" it, and so on.

Probably Python in conjunction with subprocess.Popen would be a good way of implementing.