vppinfra: improve clocks_per_second convergence

Apply exponential smoothing to the clock rate update calculation in
clib_time_verify_frequency(), with a half-life of 1 minute and a
sampling frequency of 16 seconds. Within 5 minutes or so, the
calculation converges

With each rate recalculation: reset total_cpu_time based on the kernel
timebase delta since vpp started, and the new clock rate

Improve the "show clock [verbose]" debug CLI command.

BFD echo + echo fail tests marked off until the BFD code can be
reworked a bit.

Type: fix

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I24e88a78819b12867736c875067b386ef6115c5c
diff --git a/src/vnet/bfd/bfd_main.c b/src/vnet/bfd/bfd_main.c
index 34e9804..a9a6d05 100644
--- a/src/vnet/bfd/bfd_main.c
+++ b/src/vnet/bfd/bfd_main.c
@@ -1327,7 +1327,7 @@
   bm->vlib_main = vm;
   bm->vnet_main = vnet_get_main ();
   clib_memset (&bm->wheel, 0, sizeof (bm->wheel));
-  bm->cpu_cps = vm->clib_time.clocks_per_second;
+  bm->cpu_cps = (u64) vm->clib_time.clocks_per_second;
   BFD_DBG ("cps is %.2f", bm->cpu_cps);
   bm->default_desired_min_tx_clocks =
     bfd_usec_to_clocks (bm, BFD_DEFAULT_DESIRED_MIN_TX_USEC);