Move code around to satisfy t/stest linkage

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/gettime.h b/gettime.h
index 87cc895..309ef21 100644
--- a/gettime.h
+++ b/gettime.h
@@ -15,4 +15,6 @@
 extern void fio_clock_init(void);
 extern int fio_start_gtod_thread(void);
 
+extern struct timeval *fio_tv;
+
 #endif