Fix for CVE-2014-3570 (with minor bn_asm.c revamp).

Reviewed-by: Emilia Kasper <emilia@openssl.org>
int test_mod(BIO *bp, BN_CTX *ctx)
	{
	BIGNUM *a,*b,*c,*d,*e;
	int i;

	a=BN_new();
	b=BN_new();
	c=BN_new();
	d=BN_new();
	e=BN_new();

	BN_bntest_rand(a,1024,0,0); /**/
	for (i=0; i<num0; i++)
		{
		BN_bntest_rand(b,450+i*10,0,0); /**/
		a->neg=rand_neg();
		b->neg=rand_neg();
		BN_mod(c,a,b,ctx);/**/
		if (bp != NULL)
			{
			if (!results)
				{
				BN_print(bp,a);
				BIO_puts(bp," % ");
				BN_print(bp,b);
				BIO_puts(bp," - ");
				}
			BN_print(bp,c);
			BIO_puts(bp,"\n");
			}
		BN_div(d,e,a,b,ctx);
		BN_sub(e,e,c);
		if(!BN_is_zero(e))
		    {
		    fprintf(stderr,"Modulo test failed!\n");
		    return 0;
		    }
		}
	BN_free(a);
	BN_free(b);
	BN_free(c);
	BN_free(d);
	BN_free(e);
	return(1);
	}

int test_mod(BIO *bp, BN_CTX *ctx)
	{
	BIGNUM *a,*b,*c,*d,*e;
	int i;

	a=BN_new();
	b=BN_new();
	c=BN_new();
	d=BN_new();
	e=BN_new();

	BN_bntest_rand(a,1024,0,0); /**/
	for (i=0; i<num0; i++)
		{
		BN_bntest_rand(b,450+i*10,0,0); /**/
		a->neg=rand_neg();
		b->neg=rand_neg();
		BN_mod(c,a,b,ctx);/**/
		if (bp != NULL)
			{
			if (!results)
				{
				BN_print(bp,a);
				BIO_puts(bp," % ");
				BN_print(bp,b);
				BIO_puts(bp," - ");
				}
			BN_print(bp,c);
			BIO_puts(bp,"\n");
			}
		BN_div(d,e,a,b,ctx);
		BN_sub(e,e,c);
		if(!BN_is_zero(e))
		    {
		    fprintf(stderr,"Modulo test failed!\n");
		    return 0;
		    }
		}
	BN_free(a);
	BN_free(b);
	BN_free(c);
	BN_free(d);
	BN_free(e);
	return(1);
	}
