windows: return libuv error codes in uv_poll_init()
windows: return libuv error codes in uv_poll_init()

Closes #1518

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso