Enable gtest for testing LED set operations

This patchset enables gtest to allow different combinations
of LED set operations to be verified at build time.

Change-Id: I9c2ddf82c2e23be911233b23037ee44e3ce301db
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>
diff --git a/Makefile.am b/Makefile.am
index 04dab40..9e49364 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -15,3 +15,5 @@
 
 phosphor_ledmanager_LDFLAGS = $(SYSTEMD_LIBS)
 phosphor_ledmanager_CFLAGS = $(SYSTEMD_CFLAGS)
+
+SUBDIRS = test