Link systemd

Prepare for DBus.

Change-Id: I59b63202db603b5137d7dce62e03f1cde177e675
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/Makefile.am b/Makefile.am
index 0215db3..d93b6da 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2,6 +2,8 @@
 
 phosphor_hwmon_readd_SOURCES = readd.cpp
 phosphor_hwmon_readd_LDADD = libhwmon.la
+phosphor_hwmon_readd_LDFLAGS = $(SYSTEMD_LIBS)
+phosphor_hwmon_readd_CFLAGS = $(SYSTEMD_CFLAGS)
 
 noinst_LTLIBRARIES = libhwmon.la
 libhwmon_la_SOURCES = \