Add official extension value.

Encrypt then MAC now has an official extension value, see:

http://www.ietf.org/id/draft-ietf-tls-encrypt-then-mac-02.txt
Make tls_session_secret_cb work with CVE-2014-0224 fix.

If application uses tls_session_secret_cb for session resumption
set the CCS_OK flag.
Create test/testutil.h for unit test helper macros

Defines SETUP_TEST_FIXTURE and EXECUTE_TEST, and updates ssl/heartbeat_test.c
using these macros. SETUP_TEST_FIXTURE makes use of the new TEST_CASE_NAME
macro, defined to use __func__ or __FUNCTION__ on platforms that support those
symbols, or to use the file name and line number otherwise. This should fix
several reported build problems related to lack of C99 support.