gettime: add basic init cpuclock test

Some systems claim to have a synced and constant rate tsc, even if
they don't. So add the basic cpuclock-test test as part of fio
trusting the CPU clock, to avoid using the CPU clock on a system
where the TSC truly isn't synced between CPUs.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/gettime.h b/gettime.h
index b775ef3..eb3537b 100644
--- a/gettime.h
+++ b/gettime.h
@@ -17,7 +17,7 @@
 extern void fio_gtod_init(void);
 extern void fio_clock_init(void);
 extern int fio_start_gtod_thread(void);
-extern int fio_monotonic_clocktest(void);
+extern int fio_monotonic_clocktest(int debug);
 extern void fio_local_clock_init(int);
 
 extern struct timeval *fio_tv;