sys_select: Fix compilation error on mingw, introduced on 2011-06-30. * lib/sys_select.in.h: Don't include <sys/socket.h>. Instead, include <winsock2.h>. (rpl_fd_isset, FD_ISSET): New definitions, copied from lib/sys_socket.in.h. (close, gethostname): Hide declarations from <winsock2.h>. (socket, connect, accept, bind, getpeername, getsockname, getsockopt, listen, recv, send, recvfrom, sendto, setsockopt, shutdown): Likewise. * lib/sys_socket.in.h (close, gethostname): Tweak indentation. (select): Don't override if gnulib's <sys/select.h> was already included. * lib/unistd.in.h (socket, connect, accept, bind, getpeername, getsockname, getsockopt, listen, recv, send, recvfrom, sendto, setsockopt, shutdown, select): Tweak indentation.