Comment 14 for bug 1452239

Revised patch for trunk which adds a robustification suggested in bug 1453900: We only read /proc/pid/stat{us} once right after apport starts, before it drops its privileges, to make it more obvious that you can't replace the crashing PID by a new process (with possibly different privileges). As drop_privileges() was called before reading the core dump from stdin, and thus before the originally crashing pid went away, I don't think that there was an actual bug/race here, but like this it's more explicit and cleaner code.