In _localemodule.c and selectmodule.c, remove dead code that would
cause double decrefs if run.

In addition, replace PyList_SetItem() with PyList_SET_ITEM() in cases
where a new list is populated and there is no possibility of an error.

In addition, check if the list changed size in the loop in array_array_fromlist().

select() calls are retried on EINTR (per PEP 475).  However, if a
timeout was provided and the deadline has passed after running the
signal handlers, rlist, wlist and xlist should be cleared since select(2)
left them unmodified.

Fix also return type for few other functions (clear, releasebuffer).

Although the kernel accepts any negative value for timeout, the
documented value to block indefinitely is -1.

This commit also makes the code similar to select.poll.poll().

Fix compile errors reported by HP aCC by fixing bugs introduced in 6dc57e2a20c
which do not cause trouble on clang or GCC.

Patch by Michael Osipov.

* `flags` is indeed deprecated, but there is a validation on its value for
  backwards compatibility reasons.  This adds mention of this in the docs.
* The docs say that `sizehint` is deprecated and ignored, but it is still
  used when `epoll_create1()` is unavailable. This adds mention of this in
  the docs.
* `sizehint=-1` is acceptable again, and is replaced with `FD_SETSIZE-1`.
  This is needed to have a default value available at the Python level,
  since `FD_SETSIZE` is not exposed to Python. (see: bpo-31938)
* Reject `sizehint=0` since it is invalid to pass on to `epoll_create()`.

The relevant tests have also been updated.

METH_NOARGS functions need only a single argument but they are cast
into a PyCFunction, which takes two arguments.  This triggers an
invalid function cast warning in gcc8 due to the argument mismatch.
Fix this by adding a dummy unused argument.