Add support for ppoll and pselect

This is based on huge commit 11952073af22568b from master.

Change-Id: Ib033a75b6bd659a9ccb190f8c3b4ec75aa396731
Add SOCK_CLOEXEC and SOCK_NONBLOCK socket flags.

SOCK_CLOEXEC is used to atomically set close-on-exec flag for the new
descriptor(s), and SOCK_NONBLOCK is used to mark descriptor(s) as
non-blocking.

(cherry picked from commit 43d2137af0e2f65b7febf4414e10b979aa0007bf)

Change-Id: I86c7b4d23ea410b2a2f260da6b265496cd7acb9f
Add epoll_create1

This is partial cherry-pick from cac7b9d6ec1a09814bc028e2f768db732f018891

Change-Id: I2966453cb54ba685cbe8a192070ba2e7b27b2d51
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