Include string.h (whis is in all relevant standards) instead of

#include <openssl/objects.h>

#include <openssl/err.h>

#include <openssl/asn1t.h>

#include <memory.h>

#include <string.h>

static int asn1_item_ex_combine_new(ASN1_VALUE **pval, const ASN1_ITEM *it, int combine);

static void asn1_item_clear(ASN1_VALUE **pval, const ASN1_ITEM *it);