deps: float 43e6a58d from openssl (CVE-2018-0734)

Low severity timing vulnerability in the DSA signature algorithm

Publicly disclosed but unreleased, pending OpenSSL 1.0.2q

Ref: openssl/openssl#7486
Ref: openssl/openssl#7513
Ref: https://www.openssl.org/news/secadv/20181030.txt
Ref: nodejs#23965
Upstream: openssl/openssl@a9cfb8c2
Upstream: openssl/openssl@43e6a58d

Original commit message:

    Avoid a timing attack that leaks information via a side channel that
    triggers when a BN is resized.  Increasing the size of the BNs
    prior to doing anything with them suppresses the attack.

    Thanks due to Samuel Weiser for finding and locating this.

    Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
    (Merged from openssl/openssl#7486)

Original backport commit message:

    Merge DSA reallocation timing fix CVE-2018-0734.

    Reviewed-by: Richard Levitte <levitte@openssl.org>
    (Merged from openssl/openssl#7513)

deps/openssl/openssl/crypto/dsa/dsa_ossl.c

@@ -279,7 +279,7 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
         goto err;
 
     /* Preallocate space */
-    q_bits = BN_num_bits(dsa->q);
+    q_bits = BN_num_bits(dsa->q) + sizeof(dsa->q->d[0]) * 16;
     if (!BN_set_bit(&k, q_bits)
         || !BN_set_bit(&l, q_bits)
         || !BN_set_bit(&m, q_bits))