deps: float 15d7e79 from openssl

The upstream commit fixes an incorrect initialization of memory in
rand_lib.c. This fixes all errors that are reported by valgrind during
startup.

Origin: openssl/openssl@15d7e7997e219fc

PR-URL: #28796
Fixes: #28739
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

deps/openssl/openssl/crypto/rand/rand_lib.c

@@ -235,7 +235,9 @@ size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
     struct {
         void * instance;
         int count;
-    } data = { NULL, 0 };
+    } data;
+
+    memset(&data, 0, sizeof(data));
 
     pool = rand_pool_new(0, min_len, max_len);
     if (pool == NULL)