Before modifying an EVM protected extended attribute or any other
metadata included in the HMAC calculation, the existing 'security.evm'
is verified.  This patch adds calls to integrity_audit_msg() to audit
integrity metadata failures.
Reported-by: Sven Vermeulen <sven.vermeulen@siphos.be>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>