CLEANUP: clock: stop exporting before_poll and after_poll
We don't need to export them anymore so let's make them static.
diff --git a/src/clock.c b/src/clock.c
index cd5ead7..ccb59c3 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -29,9 +29,9 @@
THREAD_LOCAL uint now_ms; /* internal monotonic date in milliseconds (may wrap) */
THREAD_LOCAL struct timeval now; /* internal monotonic date derived from real clock */
THREAD_LOCAL struct timeval date; /* the real current date (wall-clock time) */
-THREAD_LOCAL struct timeval before_poll; /* system date before calling poll() */
-THREAD_LOCAL struct timeval after_poll; /* system date after leaving poll() */
+static THREAD_LOCAL struct timeval before_poll; /* system date before calling poll() */
+static THREAD_LOCAL struct timeval after_poll; /* system date after leaving poll() */
static THREAD_LOCAL unsigned int samp_time; /* total elapsed time over current sample */
static THREAD_LOCAL unsigned int idle_time; /* total idle time over current sample */
static THREAD_LOCAL unsigned int iso_time_sec; /* last iso time value for this thread */