fix call to alloca in a loop php_api_datastore

[odaysec]

newrelic-php-agent/agent/php_api_datastore.c

Lines 57 to 60 in 765888d

	= nr_alloca(sizeof(datastore_validators[i].default_value));
	nr_strcpy(default_value, datastore_validators[i].default_value);
	nr_php_add_assoc_string(validated_params, key, default_value);

fixed php_api_datastore call to alloca in a loop, replace the use of nr_alloca with malloc to allocate memory on the heap. This ensures that memory is properly freed after each iteration, avoiding stack overflow risks. Specifically:

1. Replace nr_alloca(sizeof(datastore_validators[i].default_value)) with malloc(sizeof(datastore_validators[i].default_value)).
2. Add a call to free(default_value) after the memory is used in each iteration to prevent memory leaks.
3. Ensure no other functionality is altered.

References

• ALLOCA(3)
• a62bb80fd79866414412de6145af51bd