Provide inuse/allocated for memleak.py

To detect the memory footprint, there are 2 aspects:
1. inuse memory footprint, that is, allocated/freed memory will not be counted. Only those memory which is in use will be counted.
2. allocated memory, that is, once it is allocated, the total count is increased.
Could anyone assign it and resolve it? Thanks a lot:)

Start by inspecting memleak.py and the surrounding BCC memory-monitoring behavior to determine how its current footprint is measured. Define how in-use and total allocated memory should be exposed, then verify both values with representative allocation and freeing scenarios; the issue names no tests or other files.

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