Refactor the calloc semantic patch.

// Use calloc or realloc as appropriate instead of multiply-and-alloc

@malloc_to_calloc@

identifier f =~ "(tor_malloc|tor_malloc_zero)";

expression a, b;

@@

- tor_malloc(a * b)

+ tor_calloc(a, b)

@malloc_zero_to_calloc@

expression a, b;

@@

- tor_malloc_zero(a * b)

- f(a * b)

+ tor_calloc(a, b)

@realloc_to_reallocarray@