test: use only one main library

Use only gtest_main or gmock_main.

Change-Id: Ib6b8347560ff20d5d062baec807b1590050627c3
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 08a2537..e3468a3 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -22,7 +22,7 @@
 
 test_ldflags = \
 	-lgtest_main -lgtest \
-	-lgmock_main -lgmock \
+	-lgmock \
 	$(PTHREAD_LIBS) \
 	$(OESDK_TESTCASE_FLAGS) \
 	$(PHOSPHOR_DBUS_INTERFACES_LIBS) \