x86: Improve exception/trap debugging

Currently when an unhandled exception or trap occurs, we don't know
specifically which one happened. The CONFIG_EXCEPTION_DEBUG option
installs handlers for various exceptions and prints out details
when they happen.

Change-Id: I4d3fe4544c3e2583c4f83b306b86ac0595d9ce0e
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>