Add Certificate verification support

Call X509_verify_cert to perform the following validations:
      o Check trust settings on the root CA
      o Validity of the certificate chain by
        enabling (X509_V_ERR_CERT_HAS_EXPIRED).
    For details of the verification, refer:
    https://www.openssl.org/docs/manmaster/man1/verify.html

Change-Id: I5fcde5d34658e7b483de2715831107509f31b531
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/Makefile.am b/Makefile.am
index 7ff740a..d107521 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,7 +16,9 @@
 phosphor_certificate_manager_LDFLAGS = \
 	$(SDBUSPLUS_LIBS) \
 	$(PHOSPHOR_DBUS_INTERFACES_LIBS) \
-	-lstdc++fs
+	-lstdc++fs \
+	-lssl \
+	-lcrypto
 
 phosphor_certificate_manager_CXXFLAGS = \
 	$(SYSTEMD_CFLAGS) \