Added support for calloc as allocator function for heap security rules.

[dannytheway]

Fix: use-after-free rule for the C language gives a false positive when calloc() is used as only malloc() is supported.

All rules for heap based vulnerabilities for the C language now support the calloc() instead of just malloc().
Additionally other allocator functions can be easily added to the list.

Additional Fix: Rule use-after-free didn't consider accessing memory as *var = ... vulnerable.
So a pattern to detect direct access to pointed memory was added.

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