Report actual bytes leaked/Fix realloc tracing

[DmitriyMusatkin]

Issue #, if available:

Description of changes: Report actual bytes leaked and not number of leaks as it says in the log message.

Fix the bug with memtracer keeping incorrect records for realloc. Previous logic for tracking realloc usage was

• realloc
• untrack old
• track new Problem with that was that memtrace realloc was not thread safe as a whole. Ex. say thread 1 does a realloc operation, it calls parent realloc and then thread 2 takes control and realloc reuses address that thread 1 just released and clobbers the records for that address, so when thread 1 gets control back, record for the address will have changed and thread 1 will update tracking data incorrectly.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (4c0a9f5) 82.22% compared to head (e4ee8e7) 82.21%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1053 +/- ## ========================================== - Coverage 82.22% 82.21% -0.01% ========================================== Files 52 52 Lines 5647 5646 -1 ========================================== - Hits 4643 4642 -1 Misses 1004 1004 ``` | [Files](https://app.codecov.io/gh/awslabs/aws-c-common/pull/1053?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs) | Coverage Δ | | |---|---|---| | [source/memtrace.c](https://app.codecov.io/gh/awslabs/aws-c-common/pull/1053?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs#diff-c291cmNlL21lbXRyYWNlLmM=) | `99.54% <100.00%> (ø)` | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/awslabs/aws-c-common/pull/1053/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs)

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