crypto: return the retval of HMAC_Update

Fixes coverity scan issue 55489.

PR-URL: https://github.com/nodejs/node/pull/10891
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>

src/node_crypto.cc

@@ -3648,8 +3648,8 @@ void Hmac::HmacInit(const FunctionCallbackInfo<Value>& args) {
 bool Hmac::HmacUpdate(const char* data, int len) {
   if (!initialised_)
     return false;
-  HMAC_Update(&ctx_, reinterpret_cast<const unsigned char*>(data), len);
-  return true;
+  int r = HMAC_Update(&ctx_, reinterpret_cast<const unsigned char*>(data), len);
+  return r == 1;
 }