x86/pv: Move exception injection into {,compat_}test_all_events()
This allows paths to jump straight to {,compat_}test_all_events() and have
injection of pending exceptions happen automatically, rather than requiring
all calling paths to handle exceptions themselves.
The normal exception path is simplified as a result, and
compat_post_handle_exception() is removed entirely.
This is part of XSA-260 / CVE-2018-8897
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>