Perf: Write also BIRD version to have all the needed data in the logfile

#include <stdlib.h>

#include <time.h>

#define PLOG(msg, ...) log(L_INFO "Perf %s " msg, p->p.name, ##__VA_ARGS__)

#define PLOG(msg, ...) log(L_INFO "Perf %s %s " msg, BIRD_VERSION, p->p.name, ##__VA_ARGS__)

static inline void

random_data(void *p, uint len)