Cygwin and MSYS2 are POSIX layers implemented on top of Windows.
Use our POSIX `poll(2)` implementation of our poll abstraction.
For most other components we already have dedicated sources
implementing them in terms of APIs available on Cygwin or
providing non-implementations of components not supported.
This leaves only three components that need Cygwin-specific
implementations:
* uv_uptime: implement using sysinfo
* uv_resident_set_memory: add a placeholder returning UV_ENOSYS
* uv_cpu_info: add a placeholder returning UV_ENOSYS
Update our test suite to account for features not available
due to Cygwin platform limitations or our placeholders.
PR-URL: https://github.com/libuv/libuv/pull/1312
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>