linux: use poll api instead of select inorder to support fd > 1024. Fixes #612 and #639

[nemosupremo]

This PR replaces the usage of select with poll on linux. select has a limitation that the number of descriptors and the actual descriptor value must be lower than FD_SETSIZE which is 1024[1]. The number of descriptor isn't an issue, however if a socket is created that has an FD that is greater than 1024, this will cause libc::FD_SET to panic.

To fix this, instead of using select, we can use poll. poll does not have this limitation. This PR replaces libc::pselect with libc::poll

This fixes #612 and #639.

[1] https://linux-tips.com/t/is-it-possible-to-listen-file-descriptor-greater-than-1024-with-select/45