1) bugfix:
   - tm_time_valid_i signal from ref_clk domain was used in sys_clk
     to gate statistics in xrx_streamers_stats.vhd - likely this gating
     was not needed because statistics are done when rcvd_latency_valid_i
     is true and this should be true only when time is valid, anyway
   - added gc_sync_ffs to synchronize tm_time_valid_i to sys_clk
     (added in xrtx_streamers_stats.vhd

2) new feature
   - added initial reset of statistics when the WR node is first
     synchronized after powerup/reset.
   - this is useful so that we have a valid reset timestamp without
     a need for a management tool to reset them. So far, when a device
     was started, the reset timestamp was zero, so without additional
     action of reseting stats, it was not possible to know when the
     stats were started

TAI time is sampled from clk_ref to clk_sys domain.
Apparently, such sampling sometimes takes more than
the configured 20 periods. Likely, this is not a problem,
but the updated gc_synchronizer2 now complains. So, I
increased the sampling time to 30 periods.

When g_num_exts=0, the input of xwr_softpll_ng
clk_ext_mul_i        : in std_logic_vector(g_num_exts-1 downto 0);
was of wrong range, i.e. std_logic_vector(-1 to 0).

Function f_nonzero_vector() was added to generate
std_logic_vector(0 to 0) in the case when g_num_exts=0.

Compilation and synthesis run at any new push. Simulation run according
to CI schedule configured on OHWR.

upgrade clbv3_ref_design to VIVADO clbv3_ref_design: add valid xdc and bmm file; use generic g_direct_dmtd

add wrpc/wrc_phy16_direct_dmtd.bram (spll KP parameters times 5 due to VCXOs range 20 ppm, incremented mode master lock timeout)
wrc_phy16_direct_dmtd.bram build with:
wrpc-sw.git peter_direct_dmtd SHA 50f1c0e
ppsi.git peter_direct_dmtd SHA bf5f6de

- Add generic parameter for the SDB info of the auxiliary interface of the WRPC.
- Export pps_csync and pps_valid ports from the WRPC.

wr_nic_wrapper: Fix copyright issues.

Fix a place & route error related to the OBUF used for PPS output signal.

It's used only locally in dmtd sampler. We don't have enough global
clock nets in Virtex6 for 18-port version of WRS.