asn1/a_bitstring.c: zeroing after recallocarray

[Theo Buehler]

The memset is not needed as recallocarray(3) does the zeroing already.
(I also think the a->data == NULL check in the if clause is redundant,
but I'm just suggesting to remove a bit that confused me)

Index: asn1/a_bitstr.c
===================================================================
RCS file: /var/cvs/src/lib/libcrypto/asn1/a_bitstr.c,v
retrieving revision 1.29
diff -u -p -U7 -r1.29 a_bitstr.c
--- asn1/a_bitstr.c     20 Oct 2018 16:07:09 -0000      1.29
+++ asn1/a_bitstr.c     15 Jun 2020 12:46:00 -0000
@@ -211,16 +211,14 @@ ASN1_BIT_STRING_set_bit(ASN1_BIT_STRING 
        if ((a->length < (w + 1)) || (a->data == NULL)) {
                if (!value)
                        return(1); /* Don't need to set */
                if ((c = recallocarray(a->data, a->length, w + 1, 1)) == NULL) {
                        ASN1error(ERR_R_MALLOC_FAILURE);
                        return 0;
                }
-               if (w + 1 - a->length > 0)
-                       memset(c + a->length, 0, w + 1 - a->length);
                a->data = c;
                a->length = w + 1;
        }
        a->data[w] = ((a->data[w]) & iv) | v;
        while ((a->length > 0) && (a->data[a->length - 1] == 0))
                a->length--;