Support UpdateTimestamp log entry property

The UpdateTimestamp property says when an event log property was last
updated.  On log creation, this field is initialized with the time that
the log was created.

The only other time a log entry property can change is when the Resolved
property changes, so also added support there to update the new
UpdateTimestamp property.

While technically every property of the Entry interface is writeable,
there is no use case nor code for changing those in the field, so
UpdateTimestamp does not support those.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I9b1360b9c5424e130947045cee7b64ede6264829
diff --git a/test/Makefile.am b/test/Makefile.am
index 64aa6d8..ddd42e6 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -10,7 +10,8 @@
 	remote_logging_test_port \
 	remote_logging_test_config \
 	sdjournal_mock_test \
-	extensions_test
+	extensions_test \
+	elog_update_ts_test
 
 test_cppflags = \
 	-Igtest \
@@ -106,6 +107,13 @@
 	$(top_builddir)/xyz/openbmc_project/Logging/Internal/Manager/server.o
 extensions_test_LDFLAGS = $(test_ldflags)
 
+elog_update_ts_test_CPPFLAGS = $(test_cppflags)
+elog_update_ts_test_CXXFLAGS = $(test_cxxflags)
+elog_update_ts_test_SOURCES = elog_update_ts_test.cpp
+elog_update_ts_test_LDADD = $(test_ldadd)
+elog_update_ts_test_LDFLAGS = \
+	$(test_ldflags)
+
 # TODO Remove once the test-case failure is resolved openbmc/phosphor-logging#11
 XFAIL_TESTS = elog_errorwrap_test