add common timer.hpp unit tests

Add unit tests for timer.hpp class. These are the unit tests copied from
the phosphor-host-ipmid/softoff/test directory.

Change-Id: I9d74c6eb528f652965f43a3a4b973368ed782bf0
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 5848c67..a2ea724 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -10,7 +10,7 @@
 AM_CXXFLAGS = $(CODE_COVERAGE_CXXFLAGS)
 test_ldadd = $(top_builddir)/libsdbusplus.la $(SYSTEMD_LIBS) \
              $(OESDK_TESTCASE_FLAGS) $(CODE_COVERAGE_LIBS)
-gtest_ldadd = $(test_ldadd) $(GTEST_LIBS) $(GMOCK_LIBS) -lgmock_main
+gtest_ldadd = $(test_ldadd) $(GTEST_LIBS) $(GMOCK_LIBS) -lgmock_main -lpthread
 
 check_PROGRAMS =
 TESTS = $(check_PROGRAMS)
@@ -55,4 +55,8 @@
 vtable_vtable_SOURCES = vtable/vtable.cpp vtable/vtable_c.c
 vtable_vtable_LDADD = $(gtest_ldadd)
 
+check_PROGRAMS += timer
+timer_SOURCES = timer.cpp
+timer_LDADD = $(gtest_ldadd)
+
 endif