libcrypto: Initialize returning size_t value

This prevents the usage of uninitialized value on error in the known
hosts hasing code if invalid (empty) hostname is used.

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Reviewed-by: Sahana Prasad <sahana@redhat.com>

src/libcrypto.c

@@ -468,7 +468,7 @@ void hmac_update(HMACCTX ctx, const void *data, unsigned long len)
 
 void hmac_final(HMACCTX ctx, unsigned char *hashmacbuf, unsigned int *len)
 {
-    size_t res;
+    size_t res = 0;
     EVP_DigestSignFinal(ctx, hashmacbuf, &res);
     EVP_MD_CTX_free(ctx);
     *len = res;