src: address coverity warning in node_file.cc

[mhdawson]

Address coverity warning that looks like
it identifies a potential crash due to using
a value after it's been passed into std::move

Signed-off-by: Michael Dawson mdawson@devrus.com

[mhdawson]

This is the coverity warning and it looks like a real problem to me

1584          std::string dirname = path.substr(0,
1585                                            path.find_last_of(kPathSeparator));
    	3. Condition dirname != path, taking true branch.
1586          if (dirname != path) {
    	4. move: path is moved (indicated by std::move(path)).
1587            req_wrap->continuation_data()->PushPath(std::move(path));
1588            req_wrap->continuation_data()->PushPath(std::move(dirname));
    	5. Falling through to end of if statement.
1589          } else if (req_wrap->continuation_data()->paths().size() == 0) {
1590            err = UV_EEXIST;
1591            continue;
1592          }
1593          uv_fs_req_cleanup(req);
    	
CID 276285 (#1 of 1): Using a moved object (USE_AFTER_MOVE)
6. use_after_move: path is used after it has been already moved.
1594          MKDirpAsync(loop, req, path.c_str(),
1595                      req_wrap->continuation_data()->mode(), nullptr);
1596          break;
1597        }

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/48078/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/48093/

[mhdawson]

Landed in a01dbf1