tools/memleak: Show allocation type in print_outstanding

[jjyao]

It's useful to know the allocation type when we print out the outstanding allocations.

[jjyao]

@yonghong-song could you help review this one? Thanks!

[yonghong-song]

There is a test failure.

30/40 Test #30: py_test_tools_memleak ............***Failed    0.35 sec
  File "/bcc/tools/memleak.py", line 564
    b"\n\t\t".join(alloc.stack).decode("ascii")))
    ^
...

Please fix.

[jjyao]

Fixed.

[jjyao]

@yonghong-song when you get a chance, could you take another look?

[ekyooo]

Please squash the fix commit into the previous commit to ensure the tool's functionality is not broken in every commit.

I am curious about how the output of the allocation type is useful.