vppinfra: refactor clib_timebase_t

Add a clib_time_t * argument to clib_timebase_init(...), to encourage
client code to share the vlib_main_t's clib_time_t object.

Display the current day / date in GMT via the "show time" debug CLI.

Fix the test framework so it processes the new "show time" output format.

Type: refactor

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I5e52d57eb164b7cdb6355362d520df6928491711
diff --git a/test/framework.py b/test/framework.py
index 46f7542..c21d188 100644
--- a/test/framework.py
+++ b/test/framework.py
@@ -758,7 +758,12 @@
 
     @classmethod
     def get_vpp_time(cls):
-        return float(cls.vapi.cli('show clock').replace("Time now ", ""))
+        # processes e.g. "Time now 2.190522, Wed, 11 Mar 2020 17:29:54 GMT"
+        # returns float("2.190522")
+        timestr = cls.vapi.cli('show clock')
+        head, sep, tail = timestr.partition(',')
+        head, sep, tail = head.partition('Time now')
+        return float(tail)
 
     @classmethod
     def sleep_on_vpp_time(cls, sec):