message: Fix zend_string in http2 server.
diff: @@ -115,8 +115,7 @@ static int http_build_trailer(http_context *ctx, uchar *buffer)
  size_t index = 0;
  zval *ztrailer = sw_zend_read_property(swoole_http_response_ce_ptr, ctx->response.zobject, ZEND_STRL("trailer"), 0);
  uint32_t nv_size = ZVAL_IS_ARRAY(ztrailer) ? php_swoole_array_length(ztrailer) : 0;
  -
  - std::vector<zend::string_ptr> str_list;
  + std::vector<zend::string_ptr> zstr_list;
  if (nv_size > 0)
  {
  @@ -136,9 +135,9 @@ static int http_build_trailer(http_context *ctx, uchar *buffer)
  {
  continue;
  }
  - zend_string *str = zval_get_string(value);
  - http2_add_header(&nv[index++], key, keylen, Z_STRVAL_P(value), Z_STRLEN_P(value));
  - str_list.emplace_back(zend::string_ptr(str));
  + zend_string *zstr = zval_get_string(value);
  + http2_add_header(&nv[index++], key, keylen, ZSTR_VAL(zstr), ZSTR_LEN(zstr));
  + zstr_list.emplace_back(zend::string_ptr(zstr));
  (void) type;
  }
  SW_HASHTABLE_FOREACH_END();
  @@ -225,6 +224,7 @@ static int http2_build_header(http_context *ctx, uchar *buffer, size_t body_leng
  size_t index = 0;
  zval *zheader = sw_zend_read_property(swoole_http_response_ce_ptr, ctx->response.zobject, ZEND_STRL("header"), 1);
  nghttp2_nv *nv = (nghttp2_nv *) ecalloc(sizeof(nghttp2_nv), 8 + (ZVAL_IS_ARRAY(zheader) ? php_swoole_array_length(zheader) : 0));
  + std::vector<zend::string_ptr> zstr_list;
  assert(ctx->send_header == 0);
  @@ -241,7 +241,6 @@ static int http2_build_header(http_context *ctx, uchar *buffer, size_t body_leng
  {
  uint32_t header_flag = 0x0;
  HashTable *ht = Z_ARRVAL_P(zheader);
  - std::vector<zend::string_ptr> str_list;
  zval *value = NULL;
  char *key = NULL;
  uint32_t keylen = 0;
  @@ -271,9 +270,9 @@ static int http2_build_header(http_context *ctx, uchar *buffer, size_t body_leng
  }
  if (!ZVAL_IS_NULL(value))
  {
  - zend_string *str = zval_get_string(value);
  - http2_add_header(&nv[index++], key, keylen, Z_STRVAL_P(value), Z_STRLEN_P(value));
  - str_list.emplace_back(zend::string_ptr(str));
  + zend_string *zstr = zval_get_string(value);
  + http2_add_header(&nv[index++], key, keylen, ZSTR_VAL(zstr), ZSTR_LEN(zstr));
  + zstr_list.emplace_back(zend::string_ptr(zstr));
  }
  }
  SW_HASHTABLE_FOREACH_END();
  