Update test calloc to handle NULL return and avoid invalid memory access and skip two tests while on macOS arm64

The change updates the test code for the calloc function to handle the case where calloc returns NULL, which can happen if the nmemb or size parameter is 0 or if the function is unable to allocate memory. The updated test case explicitly checks for a NULL pointer before attempting to free it, which avoids the potential for undefined behavior caused by attempting to free a deallocated pointer. The change ensures that the test code follows the behavior described in the man page for calloc and should be portable across different systems and versions of the C standard library.

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alelievr / libft-unit-test

Update test calloc to handle NULL return and avoid invalid memory access and skip two tests while on macOS arm64 #147