epoll_pwait has a sigsetsize argument, which was unused in this case but
it caused strace to look ugly.
On epoll_ctl, don't write back the resulting event. The event isn't
written and depending on how the guest allocated the object, we could
have a 4byte overwrite.
This isn't quite a 100% clean sweep of IWYU.
There are some false positives where clang fails.
Additionally there are still a few missed in the frontend side of things
that I didn't get to
Similarly to #1064, an application could potentially pass in bad values
that could result in assertions/exceptions being thrown, so we can guard
against that.
Despite the manual saying that applications *must* not pass maxevents
less than or equal to zero, against all odds, this is still a handled
case in the kernel, so some application out there may rely on this behavior.
The vast majoirty of syscalls don't need anything in thread or frame.
So lets save an indirection for all those syscalls.
Most of the syscalls which do need Thread (or CTX via
Thread are in Thread.cpp or Memory.cpp
These have all been modifiy to fetch Thread from Frame