report: use uv_pid_t instead of custom PID_TYPE

PR-URL: https://github.com/nodejs/node/pull/25597


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>