cpu: Add callback to check architectural watchpoint match

cpu: Add callback to check architectural watchpoint match

When QEMU watchpoint matches, that is not definitely an architectural
watchpoint match yet. If it is a stop-before-access watchpoint then that
is hardly possible to ignore it after throwing a TCG exception.

A special callback is introduced to check for architectural watchpoint
match before raising a TCG exception.

Signed-off-by: Sergey Fedorov <[email protected]>
Message-id: 1454256948[email protected]
Reviewed-by: Peter Maydell <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>