Use update_approx_time() to run a test 100 days in the past.

Fixes bug21799.

changes/bug21799

@@ -0,0 +1,6 @@
+  o Minor bugfixes (tests):
+    - Run the entry_guard_parse_from_state_full test with the time set
+      to a specific date.  (The guard state that this test was parsing
+      contained guards that had expired since the test was first
+      written.) Fixes bug 21799; bugfix on 0.3.0.1-alpha.
+

src/test/test_entrynodes.c

@@ -584,6 +584,9 @@ test_entry_guard_parse_from_state_full(void *arg)
   smartlist_t *text = smartlist_new();
   char *joined = NULL;
 
+  // So nodes aren't expired
+  update_approx_time(1481621834);
+
   MOCK(entry_guard_is_listed, mock_entry_guard_is_listed);
 
   dummy_state = state;