Add unit tests for testing Signature verification functionality

Resolves openbmc/openbmc#2838

Change-Id: I60b5ca418551d404d29646fd729311adbe81290c
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 6923088..0c59399 100755
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -15,4 +15,7 @@
 	$(PHOSPHOR_LOGGING_LIBS) -lstdc++fs -lssl -lcrypto
 
 utest_SOURCES = utest.cpp
-utest_LDADD = $(top_builddir)/phosphor_version_software_manager-version.o
+
+utest_LDADD = \
+        $(top_builddir)/image_verify.cpp \
+        $(top_builddir)/version.cpp