remove libboost_system dependency

This was just a copy/paste at some point and is now failing in CI so
remove it.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I9c526e88251c160590d8642d503b07376b3c052b
diff --git a/Makefile.am b/Makefile.am
index 129f5b1..99cabb1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -20,7 +20,7 @@
 	$(PHOSPHOR_DBUS_INTERFACES_CFLAGS) $(PHOSPHOR_LOGGING_CFLAGS)
 AM_LDFLAGS = $(GMOCK_LIBS) -lgmock_main \
 	$(GTEST_LIBS) $(OESDK_TESTCASE_FLAGS) $(PTHREAD_LIBS) \
-	$(SDBUSPLUS_LIBS) -lboost_system $(SDEVENTPLUS_LIBS) \
+	$(SDBUSPLUS_LIBS) $(SDEVENTPLUS_LIBS) \
 	$(PHOSPHOR_DBUS_INTERFACES_LIBS) $(PHOSPHOR_LOGGING_LIBS)
 
 bin_PROGRAMS = \