include/exec/poison: Mark some CONFIG defines as poisoned, too

These are defined in config-target.h and thus should never be
used in common code.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1497468113-2874-3-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
