security: Pair-up Tpm and Pib in KeyChain

In this commit, we also change the HOME setting for test cases.

Change-Id: I7fa15461555b3519d9d2005c6956c167ed07d66f
Refs: #2242
Refs: #2260
diff --git a/tests/unit-tests/security/config-file-empty-home/.ndn/client.conf b/tests/unit-tests/security/config-file-empty-home/.ndn/client.conf
index e69de29..ebc2bfd 100644
--- a/tests/unit-tests/security/config-file-empty-home/.ndn/client.conf
+++ b/tests/unit-tests/security/config-file-empty-home/.ndn/client.conf
@@ -0,0 +1,4 @@
+; Empty client.conf is unfeasible in automated tests,
+; see tests/unit-tests/security/config-file-readme.txt.
+; The test is broken into two: 1) missing pib and 2) missing tpm
+pib=pib-sqlite3:/tmp/test/ndn-cxx/keychain/sqlite3-empty/
\ No newline at end of file