eal: abstract away the auxiliary vector

eal: abstract away the auxiliary vector

Rather than attempting to load the contents of the auxv directly,
prefer to use an exposed API - and if that doesn't exist then attempt
to load the vector.  This is because on some systems, when a user
is downgraded, the /proc/self/auxv file retains the old ownership
and permissions.  The original method of /proc/self/auxv is retained.

This also removes a potential abort() in the code when compiled with
NDEBUG.  A quick parse of the code shows that many (if not all) of
the CPU flag parsing isn't used internally, so it should be okay.

Signed-off-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Timothy Redaelli <tredaelli@redhat.com>